diff --git a/FEXCore/Source/CMakeLists.txt b/FEXCore/Source/CMakeLists.txt
index 26458cad9..7db99c5a7 100644
--- a/FEXCore/Source/CMakeLists.txt
+++ b/FEXCore/Source/CMakeLists.txt
@@ -70,6 +70,7 @@ set(SRCS
   Utils/LongJump.cpp
   Utils/Telemetry.cpp
   Utils/Threads.cpp
+  Utils/WorkQueueThread.cpp
   Utils/Profiler.cpp)
 
 if (ARCHITECTURE_arm64)
diff --git a/FEXCore/Source/Interface/Core/DiskCache.cpp b/FEXCore/Source/Interface/Core/DiskCache.cpp
index 65c336c0e..776cabbf7 100644
--- a/FEXCore/Source/Interface/Core/DiskCache.cpp
+++ b/FEXCore/Source/Interface/Core/DiskCache.cpp
@@ -43,7 +43,7 @@ namespace DiskCache {
     if (!ReadOnly) {
       Modes = Modes | File::FileModes::WRITE | File::FileModes::CREATE;
     }
-    FD = fextl::make_unique<File::File>(FileName.c_str(), Modes);
+    FD = fextl::make_unique<File::File>(FileName.c_str(), Modes, false);
     if (!FD->IsValid()) {
       FD.reset();
       return false;
@@ -51,7 +51,7 @@ namespace DiskCache {
 
     bool Valid = false;
     bool TookLock = false;
-    ssize_t Size = FD->Seek(0, File::SeekOp::END);
+    ssize_t Size = FD->Size();
 
     if (Size < FOZ_REF_MAGIC_SIZE && !ReadOnly) {
       if (!FD->Lock(OPEN_LOCK_TIMEOUT_MS)) {
@@ -59,16 +59,15 @@ namespace DiskCache {
         return false;
       }
       TookLock = true;
-      // seek in case someone else made it while we waited above
-      Size = FD->Seek(0, File::SeekOp::END);
+      // check size again in case someone else made it while we waited
+      Size = FD->Size();
     }
 
     if (Size == 0 && !ReadOnly) {
-      Valid = FD->Write(MesaFOZ::stream_reference_magic_and_version, FOZ_REF_MAGIC_SIZE) == FOZ_REF_MAGIC_SIZE;
+      Valid = FD->PWrite(MesaFOZ::stream_reference_magic_and_version, FOZ_REF_MAGIC_SIZE, 0) == FOZ_REF_MAGIC_SIZE;
     } else {
-      FD->Seek(0, File::SeekOp::BEGIN);
       uint8_t magic[FOZ_REF_MAGIC_SIZE];
-      if (FD->Read(magic, FOZ_REF_MAGIC_SIZE) == FOZ_REF_MAGIC_SIZE &&
+      if (FD->PRead(magic, FOZ_REF_MAGIC_SIZE, 0) == FOZ_REF_MAGIC_SIZE &&
           memcmp(magic, MesaFOZ::stream_reference_magic_and_version, FOZ_REF_MAGIC_SIZE - 1) == 0) {
         int version = magic[FOZ_REF_MAGIC_SIZE - 1];
         Valid = version <= MesaFOZ::FOSSILIZE_FORMAT_VERSION && version >= MesaFOZ::FOSSILIZE_FORMAT_MIN_COMPAT_VERSION;
@@ -85,41 +84,34 @@ namespace DiskCache {
     return Valid;
   }
 
-  bool FOZFile::ReadNextBlob(MesaFOZ::foz_payload_key& OutKey, MesaFOZ::foz_payload_header& OutHeader, fextl::vector<uint8_t>& OutBlob) {
-    if (FD->Read(OutKey.bytes, sizeof(OutKey.bytes)) != sizeof(OutKey.bytes)) {
+  ssize_t FOZFile::Size() {
+    return FD ? FD->Size() : -1;
+  }
+
+  bool FOZFile::ReadAll(fextl::vector<uint8_t>& Out) {
+    ssize_t FileSize = Size();
+    if (FileSize < FOZ_REF_MAGIC_SIZE) {
       return false;
     }
-    if (FD->Read(&OutHeader, sizeof(OutHeader)) != sizeof(OutHeader)) {
-      return false;
-    }
-    OutBlob.resize(OutHeader.payload_size);
-    if (FD->Read(OutBlob.data(), OutBlob.size()) != (ssize_t)OutBlob.size()) {
-      return false;
-    }
-    return true;
+    Out.resize((size_t)FileSize - FOZ_REF_MAGIC_SIZE);
+    return FD->PRead(Out.data(), Out.size(), FOZ_REF_MAGIC_SIZE) == (ssize_t)Out.size();
   }
 
   bool FOZFile::ReadBlob(uint64_t Offset, std::span<uint8_t> OutBlob) {
-    ssize_t SeekRet = FD->Seek(Offset, File::SeekOp::BEGIN);
-    if (SeekRet < 0) {
+    if (FD->PRead(OutBlob.data(), OutBlob.size(), Offset) != (ssize_t)OutBlob.size()) {
       return false;
     }
-    if (FD->Read(OutBlob.data(), OutBlob.size()) != (ssize_t)OutBlob.size()) {
-      return false;
-    }
-
     return true;
   }
 
   bool FOZFile::WriteBlob(const MesaFOZ::foz_payload_key& Key, std::span<const std::span<const uint8_t>> BlobChunks, uint64_t& OutBlobOffset) {
-    uint64_t WriteOffset = 0;
-    ssize_t SeekRet = FD->Seek(0, File::SeekOp::END);
-    if (SeekRet < 0) {
+    ssize_t FileSize = FD->Size();
+    if (FileSize < 0) {
       return false;
     }
-    WriteOffset = (uint64_t)SeekRet;
+    uint64_t WriteOffset = (uint64_t)FileSize;
 
-    if (FD->Write(Key.bytes, sizeof(Key.bytes)) != sizeof(Key.bytes)) {
+    if (FD->PWrite(Key.bytes, sizeof(Key.bytes), WriteOffset) != sizeof(Key.bytes)) {
       return false;
     }
     WriteOffset += sizeof(Key.bytes);
@@ -134,7 +126,7 @@ namespace DiskCache {
                                                .crc = 0, // todo? maybe
                                                .uncompressed_size = (uint32_t)TotalBlobSize};
 
-    if (FD->Write(&ScratchHeader, sizeof(ScratchHeader)) != sizeof(ScratchHeader)) {
+    if (FD->PWrite(&ScratchHeader, sizeof(ScratchHeader), WriteOffset) != sizeof(ScratchHeader)) {
       return false;
     }
     WriteOffset += sizeof(ScratchHeader);
@@ -145,9 +137,10 @@ namespace DiskCache {
       if (Chunk.size() == 0) {
         continue;
       }
-      if (FD->Write(Chunk.data(), Chunk.size()) != (ssize_t)Chunk.size()) {
+      if (FD->PWrite(Chunk.data(), Chunk.size(), WriteOffset) != (ssize_t)Chunk.size()) {
         return false;
       }
+      WriteOffset += Chunk.size();
     }
 
     return true;
@@ -166,19 +159,40 @@ namespace DiskCache {
   }
 
   void IndexedDB::PopulateIndex(Index& CacheIndex) {
-    MesaFOZ::foz_payload_key Key;
-    MesaFOZ::foz_payload_header Header;
-    fextl::vector<uint8_t> Blob;
+    fextl::vector<uint8_t> Data;
+    if (!IndexFOZ.ReadAll(Data)) {
+      return;
+    }
 
-    while (IndexFOZ.ReadNextBlob(Key, Header, Blob)) {
-      if (Blob.size() != sizeof(MesaFOZ::mesa_index_db_file_entry)) {
+    ssize_t CacheFOZSize = CacheFOZ.Size();
+    if (CacheFOZSize < 0) {
+      return;
+    }
+
+    const uint8_t* IndexDataStart = Data.data();
+    const size_t IndexDataSize = Data.size();
+    size_t ReadOffset = 0;
+    while (ReadOffset + sizeof(MesaFOZ::foz_payload_key) + sizeof(MesaFOZ::foz_payload_header) <= IndexDataSize) {
+      const auto* FOZKey = reinterpret_cast<const MesaFOZ::foz_payload_key*>(IndexDataStart + ReadOffset);
+      ReadOffset += sizeof(MesaFOZ::foz_payload_key);
+      const auto* FOZHeader = reinterpret_cast<const MesaFOZ::foz_payload_header*>(IndexDataStart + ReadOffset);
+      ReadOffset += sizeof(MesaFOZ::foz_payload_header);
+
+      if (FOZHeader->payload_size != sizeof(MesaFOZ::mesa_index_db_file_entry) || ReadOffset + FOZHeader->payload_size > IndexDataSize) {
         break;
       }
-      MesaFOZ::mesa_index_db_file_entry* IndexEntry = (MesaFOZ::mesa_index_db_file_entry*)Blob.data();
-      if (IndexEntry->hash != XXH3_64bits(Key.bytes, FOSSILIZE_BLOB_HASH_LENGTH)) {
+      const auto* IndexBlobPayload = reinterpret_cast<const MesaFOZ::mesa_index_db_file_entry*>(IndexDataStart + ReadOffset);
+      ReadOffset += FOZHeader->payload_size;
+
+      if (IndexBlobPayload->hash != XXH3_64bits(FOZKey->bytes, FOSSILIZE_BLOB_HASH_LENGTH)) {
         break;
       }
-      CacheIndex.insert({IndexEntry->hash, {this, IndexEntry->cache_db_file_offset, IndexEntry->size}});
+      // skip corrupt (carefully) so we don't have to figure that out in the hot path later
+      if (IndexBlobPayload->cache_db_file_offset > (uint64_t)CacheFOZSize ||
+          IndexBlobPayload->size > (uint64_t)CacheFOZSize - IndexBlobPayload->cache_db_file_offset) {
+        continue;
+      }
+      CacheIndex.insert({IndexBlobPayload->hash, {this, IndexBlobPayload->cache_db_file_offset, IndexBlobPayload->size}});
     }
     // could truncate/delete index if we don't end up perfectly at end here
   }
@@ -187,15 +201,18 @@ namespace DiskCache {
     return CacheFOZ.ReadBlob(Offset, OutBlob);
   }
 
-  bool IndexedDB::StoreCacheBlob(const MesaFOZ::foz_payload_key& Key, std::span<const std::span<const uint8_t>> BlobChunks, Index& Index) {
+  bool IndexedDB::StoreCacheBlob(const MesaFOZ::foz_payload_key& Key, std::span<const uint8_t> Blob, Index& Index, std::mutex& IndexMutex) {
     if (ReadOnly) {
       // shouldn't happen
       return false;
     }
     uint64_t Hash = XXH3_64bits(Key.bytes, FOSSILIZE_BLOB_HASH_LENGTH);
-    if (Index.contains(Hash)) {
-      // shouldn't really happen.. assert or something?
-      return true;
+    {
+      std::lock_guard Guard(IndexMutex);
+      if (Index.contains(Hash)) {
+        // shouldn't really happen.. assert or something?
+        return true;
+      }
     }
 
     if (!CacheFOZ.Lock(STORE_LOCK_TIMEOUT_MS) || !IndexFOZ.Lock(STORE_LOCK_TIMEOUT_MS)) {
@@ -205,6 +222,7 @@ namespace DiskCache {
     }
 
     // write cache side first so we get offset for index
+    std::span<const uint8_t> BlobChunks[] = {Blob};
     uint64_t BlobOffset = 0;
     if (!CacheFOZ.WriteBlob(Key, BlobChunks, BlobOffset)) {
       CacheFOZ.Unlock();
@@ -212,13 +230,8 @@ namespace DiskCache {
       return false;
     }
 
-    uint64_t TotalBlobSize = 0;
-    for (const std::span<const uint8_t>& Chunk : BlobChunks) {
-      TotalBlobSize += Chunk.size();
-    }
-
     MesaFOZ::mesa_index_db_file_entry IndexEntry {.hash = Hash,
-                                                  .size = (uint32_t)TotalBlobSize,
+                                                  .size = (uint32_t)Blob.size(),
                                                   .last_access_time = 0, // todo..
                                                   .cache_db_file_offset = BlobOffset};
 
@@ -233,7 +246,8 @@ namespace DiskCache {
     CacheFOZ.Unlock();
     IndexFOZ.Unlock();
 
-    Index[Hash] = {this, BlobOffset, (uint32_t)TotalBlobSize};
+    std::lock_guard Guard(IndexMutex);
+    Index[Hash] = {this, BlobOffset, (uint32_t)Blob.size()};
     return true;
   }
 
@@ -300,13 +314,16 @@ namespace DiskCache {
       // advance to next
       RONames.remove_prefix(Delim + 1);
     }
+
+    if (IsWritingDiskCache()) {
+      Writer = fextl::make_unique<WorkQueueThread>();
+    }
   }
 
   std::optional<CodeHitData> DiskCache::Lookup(Core::InternalThreadState* Thread, const ExecutableFileSectionInfo& Region, uint64_t GuestRIP) {
     if (!IsReadingDiskCache()) {
       return std::nullopt;
     }
-    std::lock_guard Guard(Lock);
     uint64_t ModuleOffset = GuestRIP - Region.FileStartVA;
 
     // todo move key making to a helper once we have options and stuff (see Store)
@@ -314,12 +331,18 @@ namespace DiskCache {
     memcpy(Key.bytes, &ModuleOffset, sizeof(ModuleOffset));
 
     uint64_t Hash = XXH3_64bits(Key.bytes, FOSSILIZE_BLOB_HASH_LENGTH);
-    auto It = Index.find(Hash);
-    if (It == Index.end()) {
-      // definite miss
-      return std::nullopt;
+
+    IndexEntry Entry;
+    {
+      std::lock_guard Guard(IndexLock);
+      auto It = Index.find(Hash);
+      if (It == Index.end()) {
+        // definite miss
+        return std::nullopt;
+      }
+      // we can't hold onto the iterator, the map may shift while we don't hold the lock
+      Entry = It->second;
     }
-    const IndexEntry& Entry = It->second;
     // found a key hash match, could still be a miss, read the blob and verify more
     CodeHitData HitData;
     HitData.Blob.resize(Entry.Size);
@@ -405,6 +428,25 @@ namespace DiskCache {
     return HitData;
   }
 
+  static inline bool IsRelocationInBlock(const FEXCore::CPU::Relocation& Reloc, const CPU::CPUBackend::CompiledCode& CompiledCode) {
+    return Reloc.Header.Offset >= CompiledCode.HostCodeOffset && Reloc.Header.Offset < CompiledCode.HostCodeOffset + CompiledCode.Size;
+  }
+
+  struct DiskCache::CacheStoreWorkItem final : WorkQueueThread::WorkItem {
+    DiskCache* Self;
+    IndexedDB* DB;
+    MesaFOZ::foz_payload_key Key;
+    fextl::vector<uint8_t> Blob;
+    CacheStoreWorkItem(DiskCache* Self, IndexedDB* DB, const MesaFOZ::foz_payload_key& Key, fextl::vector<uint8_t>&& Blob)
+      : Self(Self)
+      , DB(DB)
+      , Key(Key)
+      , Blob(std::move(Blob)) {}
+    void Run() override {
+      DB->StoreCacheBlob(Key, Blob, Self->Index, Self->IndexLock);
+    }
+  };
+
   bool DiskCache::Store(Core::InternalThreadState* Thread, const ExecutableFileSectionInfo& Region, uint64_t GuestRIP,
                         std::span<const uint8_t> GuestCode, const CPU::CPUBackend::CompiledCode& CompiledCode,
                         std::span<const FEXCore::CPU::Relocation> Relocations, const Frontend::Decoder::DecodedBlockInformation* DecodedBlockInfo) {
@@ -414,13 +456,12 @@ namespace DiskCache {
     if (!DecodedBlockInfo) {
       return false;
     }
-    std::lock_guard Guard(Lock);
 
     // check for any reloc targets outside of our jurisdiction
     // todo what are they exactly? caching those blocks is great when it works, so need to figure this out and make finer-grained if we can
     if (RelocationFilter) {
       for (const auto& Reloc : Relocations) {
-        if (Reloc.Header.Offset < CompiledCode.HostCodeOffset || Reloc.Header.Offset >= CompiledCode.HostCodeOffset + CompiledCode.Size) {
+        if (!IsRelocationInBlock(Reloc, CompiledCode)) {
           continue;
         }
         if (Reloc.Header.Type != CPU::RelocationTypes::RELOC_GUEST_RIP_LITERAL && Reloc.Header.Type != CPU::RelocationTypes::RELOC_GUEST_RIP_MOVE) {
@@ -438,23 +479,70 @@ namespace DiskCache {
       }
     }
 
-    // pack entrypoints to disk format
-    fextl::vector<BlobEntryPoint> CacheEntryPoints;
-    CacheEntryPoints.reserve(CompiledCode.EntryPoints.size());
-
-    for (auto [GuestAddr, HostAddr] : CompiledCode.EntryPoints) {
-      CacheEntryPoints.push_back({GuestAddr - Region.FileStartVA, uint32_t(HostAddr - CompiledCode.BlockBegin)});
-    }
-
-    // pack relocations to disk format
-    fextl::vector<BlobSmallRelocation> SmallRelocs;
-    fextl::vector<BlobThunkRelocation> ThunkRelocs;
-
-    // todo discover sizes first and reserve vecs?
-
+    uint32_t SmallRelocCount = 0;
+    uint32_t ThunkRelocCount = 0;
     for (const auto& Reloc : Relocations) {
       // relocs aren't cleared every time if IsGeneratingCache, so filter just in case
-      if (Reloc.Header.Offset < CompiledCode.HostCodeOffset || Reloc.Header.Offset >= CompiledCode.HostCodeOffset + CompiledCode.Size) {
+      if (!IsRelocationInBlock(Reloc, CompiledCode)) {
+        continue;
+      }
+      if (Reloc.Header.Type == CPU::RelocationTypes::RELOC_NAMED_THUNK_MOVE) {
+        ThunkRelocCount++;
+      } else {
+        SmallRelocCount++;
+      }
+    }
+
+    const uint32_t EntryPointCount = (uint32_t)CompiledCode.EntryPoints.size();
+    const uint32_t TouchedGuestPagesCount = DecodedBlockInfo ? (uint32_t)DecodedBlockInfo->CodePages.size() : 0;
+
+    const size_t HeaderOffset = 0;
+    const size_t HostCodeOffset = HeaderOffset + sizeof(BlobFixedHeader);
+    const size_t EntryPointsOffset = HostCodeOffset + CompiledCode.Size;
+    const size_t SmallRelocsOffset = EntryPointsOffset + EntryPointCount * sizeof(BlobEntryPoint);
+    const size_t ThunkRelocsOffset = SmallRelocsOffset + SmallRelocCount * sizeof(BlobSmallRelocation);
+    const size_t TouchedGuestPagesOffset = ThunkRelocsOffset + ThunkRelocCount * sizeof(BlobThunkRelocation);
+    const size_t GuestCodeOffset = TouchedGuestPagesOffset + TouchedGuestPagesCount * sizeof(int64_t);
+    const size_t TotalSize = GuestCodeOffset + GuestCode.size();
+
+    // we'll copy everything into here and pass it to the Writer, then return to caller quickly
+    fextl::vector<uint8_t> Blob;
+    Blob.resize(TotalSize);
+    uint8_t* BlobData = Blob.data();
+
+    uint64_t ModuleOffset = GuestRIP - Region.FileStartVA;
+
+    // todo also copy/hash options that affect codegen into the key
+    // todo should try to keep the key ascii i think?
+    MesaFOZ::foz_payload_key Key = {};
+    memcpy(Key.bytes, &ModuleOffset, sizeof(ModuleOffset));
+
+    BlobFixedHeader Header {
+      .GuestSize = (uint32_t)GuestCode.size(),
+      .HostSize = (uint32_t)CompiledCode.Size,
+      .EntryPointCount = EntryPointCount,
+      .SmallRelocCount = SmallRelocCount,
+      .ThunkRelocCount = ThunkRelocCount,
+      .TouchedGuestPagesCount = TouchedGuestPagesCount,
+      .GuestHash = XXH3_128bits(GuestCode.data(), GuestCode.size()),
+    };
+    memcpy(BlobData + HeaderOffset, &Header, sizeof(Header));
+    memcpy(BlobData + HostCodeOffset, CompiledCode.BlockBegin, CompiledCode.Size);
+
+    // pack and relocate entrypoints
+    auto* EntryPoints = reinterpret_cast<BlobEntryPoint*>(BlobData + EntryPointsOffset);
+    uint32_t EntryIdx = 0;
+    for (auto [GuestAddr, HostAddr] : CompiledCode.EntryPoints) {
+      EntryPoints[EntryIdx++] = {GuestAddr - Region.FileStartVA, uint32_t(HostAddr - CompiledCode.BlockBegin)};
+    }
+
+    // pack relocations
+    auto* SmallRelocs = reinterpret_cast<BlobSmallRelocation*>(BlobData + SmallRelocsOffset);
+    auto* ThunkRelocs = reinterpret_cast<BlobThunkRelocation*>(BlobData + ThunkRelocsOffset);
+    uint32_t SmallIdx = 0;
+    uint32_t ThunkIdx = 0;
+    for (const auto& Reloc : Relocations) {
+      if (!IsRelocationInBlock(Reloc, CompiledCode)) {
         continue;
       }
       // re-relocate :harold:
@@ -468,7 +556,7 @@ namespace DiskCache {
         SmallReloc.Offset = LocalOffset;
         SmallReloc.Type = uint8_t(Reloc.Header.Type);
         SmallReloc.Named.Symbol = uint32_t(Reloc.NamedSymbolLiteral.Symbol);
-        SmallRelocs.push_back(SmallReloc);
+        SmallRelocs[SmallIdx++] = SmallReloc;
         break;
       }
       case CPU::RelocationTypes::RELOC_GUEST_RIP_LITERAL: {
@@ -476,7 +564,7 @@ namespace DiskCache {
         SmallReloc.Offset = LocalOffset;
         SmallReloc.Type = uint8_t(Reloc.Header.Type);
         SmallReloc.RIPLiteral.GuestRIP = Reloc.GuestRIP.GuestRIP - GuestRIP;
-        SmallRelocs.push_back(SmallReloc);
+        SmallRelocs[SmallIdx++] = SmallReloc;
         break;
       }
       case CPU::RelocationTypes::RELOC_GUEST_RIP_MOVE: {
@@ -485,7 +573,7 @@ namespace DiskCache {
         SmallReloc.Type = uint8_t(Reloc.Header.Type);
         SmallReloc.RIPMove.RegisterIndex = Reloc.GuestRIP.RegisterIndex;
         SmallReloc.RIPMove.GuestRIP = Reloc.GuestRIP.GuestRIP - GuestRIP;
-        SmallRelocs.push_back(SmallReloc);
+        SmallRelocs[SmallIdx++] = SmallReloc;
         break;
       }
       case CPU::RelocationTypes::RELOC_NAMED_THUNK_MOVE: {
@@ -493,50 +581,25 @@ namespace DiskCache {
         BigReloc.Offset = LocalOffset;
         BigReloc.RegisterIndex = Reloc.NamedThunkMove.RegisterIndex;
         memcpy(BigReloc.SymbolHash, &Reloc.NamedThunkMove.Symbol, sizeof(BigReloc.SymbolHash));
-        ThunkRelocs.push_back(BigReloc);
+        ThunkRelocs[ThunkIdx++] = BigReloc;
         break;
       }
       }
     }
 
-    // pack touched pages, relative to GuestRIP
+    // relocate touched pages relative to GuestRIP
     // in theory we could save some size here, unlikely we need all 64bits
-    fextl::vector<int64_t> GuestPageOffsets;
-    if (DecodedBlockInfo) {
-      GuestPageOffsets.reserve(DecodedBlockInfo->CodePages.size());
-      for (auto& GuestPage : DecodedBlockInfo->CodePages) {
-        GuestPageOffsets.push_back(GuestPage - GuestRIP);
-      }
+    auto* PageOffsets = reinterpret_cast<int64_t*>(BlobData + TouchedGuestPagesOffset);
+    uint32_t PageIdx = 0;
+    for (auto GuestPage : DecodedBlockInfo->CodePages) {
+      PageOffsets[PageIdx++] = GuestPage - GuestRIP;
     }
 
-    uint64_t ModuleOffset = GuestRIP - Region.FileStartVA;
+    memcpy(BlobData + GuestCodeOffset, GuestCode.data(), GuestCode.size());
 
-    // todo also copy/hash options that affect codegen into the key
-    // todo should try to keep the key ascii i think?
-    MesaFOZ::foz_payload_key Key = {};
-    memcpy(Key.bytes, &ModuleOffset, sizeof(ModuleOffset));
-
-    BlobFixedHeader Header {
-      .GuestSize = (uint32_t)GuestCode.size(),
-      .HostSize = (uint32_t)CompiledCode.Size,
-      .EntryPointCount = (uint32_t)CacheEntryPoints.size(),
-      .SmallRelocCount = (uint32_t)SmallRelocs.size(),
-      .ThunkRelocCount = (uint32_t)ThunkRelocs.size(),
-      .TouchedGuestPagesCount = (uint32_t)GuestPageOffsets.size(),
-      .GuestHash = XXH3_128bits(GuestCode.data(), GuestCode.size()),
-    };
-
-    std::span<const uint8_t> BlobChunks[] = {
-      {(const uint8_t*)&Header, sizeof(Header)},
-      {(const uint8_t*)CompiledCode.BlockBegin, CompiledCode.Size},
-      {(const uint8_t*)CacheEntryPoints.data(), CacheEntryPoints.size() * sizeof(BlobEntryPoint)},
-      {(const uint8_t*)SmallRelocs.data(), SmallRelocs.size() * sizeof(BlobSmallRelocation)},
-      {(const uint8_t*)ThunkRelocs.data(), ThunkRelocs.size() * sizeof(BlobThunkRelocation)},
-      {(const uint8_t*)GuestPageOffsets.data(), GuestPageOffsets.size() * sizeof(int64_t)},
-      GuestCode,
-    };
-
-    return RWCacheDB->StoreCacheBlob(Key, BlobChunks, Index);
+    // hand the rest off to the writer thread
+    Writer->QueueWork(fextl::make_unique<CacheStoreWorkItem>(this, RWCacheDB.get(), Key, std::move(Blob)));
+    return true;
   }
 
 } // namespace DiskCache
diff --git a/FEXCore/Source/Utils/WorkQueueThread.cpp b/FEXCore/Source/Utils/WorkQueueThread.cpp
new file mode 100644
index 000000000..1ca2eccfb
--- /dev/null
+++ b/FEXCore/Source/Utils/WorkQueueThread.cpp
@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: MIT
+#include <FEXCore/Utils/WorkQueueThread.h>
+#include <FEXCore/Utils/LogManager.h>
+
+namespace FEXCore {
+
+WorkQueueThread::WorkQueueThread() {
+  Thread = FEXCore::Threads::Thread::Create(ThreadEntry, this);
+}
+
+WorkQueueThread::~WorkQueueThread() {
+  {
+    std::unique_lock lk {Mutex};
+    Stop = true;
+  }
+  CV.notify_one();
+
+  if (Thread && Thread->joinable()) {
+    Thread->join(nullptr);
+  }
+}
+
+void WorkQueueThread::QueueWork(fextl::unique_ptr<WorkItem> Work) {
+  {
+    std::unique_lock lk {Mutex};
+    Queue.push_back(std::move(Work));
+  }
+  CV.notify_one();
+}
+
+void WorkQueueThread::ThreadProc() {
+  while (true) {
+    fextl::unique_ptr<WorkItem> Work;
+    {
+      std::unique_lock lk {Mutex};
+      while (!(Stop || !Queue.empty())) {
+        CV.wait(lk);
+      }
+      if (Queue.empty()) {
+        // nothing to do? must be stopping
+        LOGMAN_THROW_A_FMT(Stop, "WorkQueueThread wakes up empty but no Stop?");
+        return;
+      }
+
+      Work = std::move(Queue.front());
+      Queue.pop_front();
+    }
+
+    Work->Run();
+    // Work is destroyed here
+  }
+}
+
+} // namespace FEXCore
diff --git a/FEXCore/include/FEXCore/Core/DiskCache.h b/FEXCore/include/FEXCore/Core/DiskCache.h
index c3abac6ee..cdf3bbc0f 100644
--- a/FEXCore/include/FEXCore/Core/DiskCache.h
+++ b/FEXCore/include/FEXCore/Core/DiskCache.h
@@ -7,6 +7,7 @@
 #include "Interface/Core/CPUBackend.h"
 #include "FEXCore/Config/Config.h"
 #include "FEXCore/Utils/File.h"
+#include "FEXCore/Utils/WorkQueueThread.h"
 #include "FEXCore/fextl/memory.h"
 #include <FEXCore/fextl/string.h>
 #include <FEXCore/fextl/unordered_set.h>
@@ -123,7 +124,8 @@ namespace DiskCache {
       }
       return FD->Unlock();
     }
-    bool ReadNextBlob(MesaFOZ::foz_payload_key& OutKey, MesaFOZ::foz_payload_header& OutHeader, fextl::vector<uint8_t>& OutBlob);
+    ssize_t Size();
+    bool ReadAll(fextl::vector<uint8_t>& Out); // from first blob
     bool ReadBlob(uint64_t Offset, std::span<uint8_t> OutBlob);
     bool WriteBlob(const MesaFOZ::foz_payload_key& Key, std::span<const std::span<const uint8_t>> BlobChunks, uint64_t& OutBlobOffset);
 
@@ -140,11 +142,11 @@ namespace DiskCache {
     bool Open(const fextl::string& CacheDBName, bool ReadOnly);
     void PopulateIndex(Index& CacheIndex);
     bool ReadCacheBlob(uint64_t Offset, std::span<uint8_t> OutBlob);
-    bool StoreCacheBlob(const MesaFOZ::foz_payload_key& Key, std::span<const std::span<const uint8_t>> BlobChunks, Index& CacheIndex);
+    bool StoreCacheBlob(const MesaFOZ::foz_payload_key& Key, std::span<const uint8_t> Blob, Index& CacheIndex, std::mutex& IndexMutex);
 
   private:
-    // give up after 2ms of trying to store - when we have an async thread we can increase this
-    static constexpr uint32_t STORE_LOCK_TIMEOUT_MS = 2;
+    // stores run on the Writer, so returning quick isn't as important
+    static constexpr uint32_t STORE_LOCK_TIMEOUT_MS = 1000;
 
     FOZFile CacheFOZ;
     FOZFile IndexFOZ;
@@ -174,7 +176,11 @@ namespace DiskCache {
     fextl::vector<fextl::unique_ptr<IndexedDB>> ROCacheDBs;
     fextl::unique_ptr<IndexedDB> RWCacheDB;
     Index Index;
-    std::mutex Lock;
+    std::mutex IndexLock;
+    struct CacheStoreWorkItem;
+
+    // the Writer holds references to all this stuff above and needs to be last
+    fextl::unique_ptr<WorkQueueThread> Writer;
 
     FEX_CONFIG_OPT(EnableDiskCache, DISKCACHE);
     FEX_CONFIG_OPT(RelocationFilter, DISKCACHERELOCATIONFILTER);
diff --git a/FEXCore/include/FEXCore/Utils/File.h b/FEXCore/include/FEXCore/Utils/File.h
index a288c166e..140e40a1c 100644
--- a/FEXCore/include/FEXCore/Utils/File.h
+++ b/FEXCore/include/FEXCore/Utils/File.h
@@ -3,6 +3,7 @@
 #include <FEXCore/fextl/allocator.h>
 #include <FEXCore/fextl/string.h>
 #include <FEXCore/Utils/EnumOperators.h>
+#include "FEXCore/Utils/LogManager.h"
 
 #include <chrono>
 #include <thread>
@@ -11,6 +12,7 @@
 #include <fcntl.h>
 #include <unistd.h>
 #include <sys/file.h>
+#include <sys/stat.h>
 #else
 #define WIN32_LEAN_AND_MEAN
 #include <windows.h>
@@ -43,7 +45,8 @@ public:
 
   File() = default;
 
-  File(const char* Filepath, FileModes Modes) {
+  File(const char* Filepath, FileModes Modes, bool Seekable = true)
+    : Seekable {Seekable} {
 #ifndef _WIN32
     auto Disp = TranslateModes(Modes);
     Handle = open(Filepath, Disp, DEFAULT_USER_PERMS);
@@ -75,6 +78,10 @@ public:
    * @return The number of bytes actually written or -1 on error.
    */
   ssize_t Write(const void* Buffer, size_t Bytes) {
+    if (!Seekable) {
+      LOGMAN_THROW_A_FMT(false, "Can't use non-positioned ops on a non-seekable file!");
+      return -1;
+    }
 #ifndef _WIN32
     return write(Handle, Buffer, Bytes);
 #else
@@ -101,6 +108,10 @@ public:
    * @return The number of bytes read or -1 on error.
    */
   ssize_t Read(void* Buffer, size_t Bytes) {
+    if (!Seekable) {
+      LOGMAN_THROW_A_FMT(false, "Can't use non-positioned ops on a non-seekable file!");
+      return -1;
+    }
 #ifndef _WIN32
     return read(Handle, Buffer, Bytes);
 #else
@@ -114,6 +125,48 @@ public:
 #endif
   }
 
+  ssize_t PRead(void* Buffer, size_t Bytes, uint64_t Offset) {
+    if (Seekable) {
+      LOGMAN_THROW_A_FMT(false, "Can't use positioned ops on a seekable file!");
+      return -1;
+    }
+#ifndef _WIN32
+    return pread(Handle, Buffer, Bytes, Offset);
+#else
+    DWORD BytesRead {};
+    OVERLAPPED Overlapped {};
+    Overlapped.Offset = static_cast<DWORD>(Offset);
+    Overlapped.OffsetHigh = static_cast<DWORD>(Offset >> 32);
+    auto Result = ReadFile(Handle, Buffer, Bytes, &BytesRead, &Overlapped);
+    if (Result) {
+      return BytesRead;
+    }
+    // Some error, match Linux side.
+    return -1;
+#endif
+  }
+
+  ssize_t PWrite(const void* Buffer, size_t Bytes, uint64_t Offset) {
+    if (Seekable) {
+      LOGMAN_THROW_A_FMT(false, "Can't use positioned ops on a seekable file!");
+      return -1;
+    }
+#ifndef _WIN32
+    return pwrite(Handle, Buffer, Bytes, Offset);
+#else
+    DWORD BytesWritten {};
+    OVERLAPPED Overlapped {};
+    Overlapped.Offset = static_cast<DWORD>(Offset);
+    Overlapped.OffsetHigh = static_cast<DWORD>(Offset >> 32);
+    auto Result = WriteFile(Handle, Buffer, Bytes, &BytesWritten, &Overlapped);
+    if (Result) {
+      return BytesWritten;
+    }
+    // Some error, match Linux side.
+    return -1;
+#endif
+  }
+
   bool Lock(uint32_t TimeoutMS) {
     for (uint32_t i = 0;; ++i) {
       if (TryLock()) {
@@ -202,6 +255,22 @@ public:
 #endif
   }
 
+  ssize_t Size() {
+#ifndef _WIN32
+    struct stat st;
+    if (fstat(Handle, &st) != 0) {
+      return -1;
+    }
+    return st.st_size;
+#else
+    LARGE_INTEGER FileSize;
+    if (!GetFileSizeEx(Handle, &FileSize)) {
+      return -1;
+    }
+    return FileSize.QuadPart;
+#endif
+  }
+
   /**
    * @brief Seek the file pointer location.
    *
@@ -211,6 +280,10 @@ public:
    * @return The current file pointer location or -1.
    */
   ssize_t Seek(ssize_t Distance, SeekOp Op) {
+    if (!Seekable) {
+      LOGMAN_THROW_A_FMT(false, "Can't use non-positioned ops on a non-seekable file!");
+      return -1;
+    }
 #ifndef _WIN32
     return lseek(Handle, Distance, TranslateSeek(Op));
 #else
@@ -227,10 +300,11 @@ public:
 
 protected:
 
-  File(FileHandleType Handle, bool ShouldClose)
+  File(FileHandleType Handle, bool ShouldClose, bool Seekable = true)
     : ShouldClose {ShouldClose}
     , IsValidHandle {true}
-    , Handle {Handle} {}
+    , Handle {Handle}
+    , Seekable {Seekable} {}
 private:
   bool TryLock() {
     if (Locked) {
@@ -257,6 +331,7 @@ private:
   bool IsValidHandle {};
 
   FileHandleType Handle {};
+  bool Seekable = true;
   bool Locked = false;
 #ifndef _WIN32
   static constexpr int DEFAULT_USER_PERMS = S_IRWXU | S_IRWXG | S_IRWXO;
diff --git a/FEXCore/include/FEXCore/Utils/WorkQueueThread.h b/FEXCore/include/FEXCore/Utils/WorkQueueThread.h
new file mode 100644
index 000000000..e9ff114a9
--- /dev/null
+++ b/FEXCore/include/FEXCore/Utils/WorkQueueThread.h
@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: MIT
+#pragma once
+
+#include <FEXCore/Utils/Threads.h>
+#include <FEXCore/fextl/deque.h>
+#include <FEXCore/fextl/memory.h>
+
+#include <condition_variable>
+#include <mutex>
+
+namespace FEXCore {
+
+class WorkQueueThread {
+public:
+  // destroyed after Run()
+  struct WorkItem {
+    virtual ~WorkItem() = default;
+    virtual void Run() = 0;
+  };
+
+  WorkQueueThread();
+  ~WorkQueueThread();
+
+  void QueueWork(fextl::unique_ptr<WorkItem> Work);
+
+private:
+  // static function for the ::Thread to refer to
+  static void* ThreadEntry(void* Self) {
+    static_cast<WorkQueueThread*>(Self)->ThreadProc();
+    return nullptr;
+  }
+  void ThreadProc();
+
+  std::mutex Mutex;
+  std::condition_variable CV;
+  fextl::deque<fextl::unique_ptr<WorkItem>> Queue;
+  bool Stop = false;
+
+  fextl::unique_ptr<FEXCore::Threads::Thread> Thread;
+};
+} // namespace FEXCore
diff --git a/Source/Windows/ARM64EC/Module.cpp b/Source/Windows/ARM64EC/Module.cpp
index 2be579233..234489a7b 100644
--- a/Source/Windows/ARM64EC/Module.cpp
+++ b/Source/Windows/ARM64EC/Module.cpp
@@ -36,6 +36,7 @@ $end_info$
 #include "Common/Exception.h"
 #include "Common/ImageTracker.h"
 #include "Common/InvalidationTracker.h"
+#include "Common/Threads.h"
 #include "Common/OvercommitTracker.h"
 #include "Common/TSOHandlerConfig.h"
 #include "Common/CPUFeatures.h"
@@ -581,6 +582,7 @@ NTSTATUS ProcessInit() {
   InitSyscalls();
 
   FEX::Windows::InitCRTProcess();
+  FEX::Windows::SetupThreadHandlers();
   const auto ExecutablePath = FEX::Windows::GetExecutableFilePath();
   const auto ExecutableName = FEX::Windows::BaseName(ExecutablePath);
   FEX::Config::LoadConfig(fextl::string {ExecutableName}, _environ, FEX::ReadPortabilityInformation());
diff --git a/Source/Windows/Common/CMakeLists.txt b/Source/Windows/Common/CMakeLists.txt
index a9cdeac60..0a65c997f 100644
--- a/Source/Windows/Common/CMakeLists.txt
+++ b/Source/Windows/Common/CMakeLists.txt
@@ -14,7 +14,8 @@ add_library(CommonWindows STATIC
   SHMStats.cpp
   InvalidationTracker.cpp
   ImageTracker.cpp
-  Logging.cpp)
+  Logging.cpp
+  Threads.cpp)
 
 target_link_libraries(CommonWindows FEXCore_Base)
 target_include_directories(CommonWindows PRIVATE "${CMAKE_SOURCE_DIR}/Source/Windows/include/")
diff --git a/Source/Windows/Common/Threads.cpp b/Source/Windows/Common/Threads.cpp
new file mode 100644
index 000000000..55f741334
--- /dev/null
+++ b/Source/Windows/Common/Threads.cpp
@@ -0,0 +1,95 @@
+// SPDX-License-Identifier: MIT
+#include "Threads.h"
+#include "CRT/CRT.h"
+
+#include <FEXCore/Utils/LogManager.h>
+#include <FEXCore/Utils/Threads.h>
+#include <FEXCore/fextl/memory.h>
+
+#include <winternl.h>
+#include <windows.h>
+
+namespace FEX::Windows {
+namespace WinThreadImpl {
+  class Thread final : public FEXCore::Threads::Thread {
+  public:
+    Thread(FEXCore::Threads::ThreadFunc Func, void* Arg)
+      : UserFunc {Func}
+      , UserArg {Arg} {
+      // hide everything from guest, don't initialize anything, we'll do that manually in RunThread()
+      const ULONG CreateFlags = THREAD_CREATE_FLAGS_SKIP_THREAD_ATTACH | THREAD_CREATE_FLAGS_HIDE_FROM_DEBUGGER |
+                                THREAD_CREATE_FLAGS_SKIP_LOADER_INIT | THREAD_CREATE_FLAGS_BYPASS_PROCESS_FREEZE;
+      NTSTATUS Status = NtCreateThreadEx(&Handle, THREAD_ALL_ACCESS, nullptr, GetCurrentProcess(),
+                                         reinterpret_cast<PRTL_THREAD_START_ROUTINE>(&Thread::RunThread), this, CreateFlags, 0, 0, 0, nullptr);
+      if (Status < 0) {
+        LogMan::Msg::EFmt("NtCreateThreadEx failed: 0x{:x}", static_cast<uint32_t>(Status));
+        Handle = nullptr;
+      }
+    }
+
+    bool joinable() override {
+      return Handle != nullptr;
+    }
+
+    bool join(void** ret) override {
+      if (!Handle) {
+        return false;
+      }
+      NtWaitForSingleObject(Handle, FALSE, nullptr);
+      if (ret) {
+        *ret = ReturnValue;
+      }
+      return true;
+    }
+
+    bool detach() override {
+      // almost no-op, it's already detached, just deref handle
+      if (Handle) {
+        NtClose(Handle);
+        Handle = nullptr;
+      }
+      return true;
+    }
+
+    bool IsSelf() override {
+      return TID == GetCurrentThreadId();
+    }
+
+    ~Thread() override {
+      if (Handle) {
+        NtClose(Handle);
+      }
+    }
+
+  private:
+    static void RunThread(Thread* This) {
+      This->TID = GetCurrentThreadId();
+      // do initialization we skipped earlier here around the user entrypoint
+      FEX::Windows::InitCRTThread();
+      This->ReturnValue = This->UserFunc(This->UserArg);
+      FEX::Windows::DeinitCRTThread();
+      NtTerminateThread(GetCurrentThread(), 0);
+    }
+
+    FEXCore::Threads::ThreadFunc UserFunc;
+    void* UserArg;
+    HANDLE Handle {};
+    DWORD TID {};
+    void* ReturnValue {};
+  };
+
+  fextl::unique_ptr<FEXCore::Threads::Thread> CreateThread(FEXCore::Threads::ThreadFunc Func, void* Arg) {
+    return fextl::make_unique<Thread>(Func, Arg);
+  }
+
+  void CleanupAfterFork() {}
+} // namespace WinThreadImpl
+
+void SetupThreadHandlers() {
+  FEXCore::Threads::Pointers Ptrs = {
+    .CreateThread = WinThreadImpl::CreateThread,
+    .CleanupAfterFork = WinThreadImpl::CleanupAfterFork,
+  };
+  FEXCore::Threads::Thread::SetInternalPointers(Ptrs);
+}
+} // namespace FEX::Windows
diff --git a/Source/Windows/Common/Threads.h b/Source/Windows/Common/Threads.h
new file mode 100644
index 000000000..5e2606901
--- /dev/null
+++ b/Source/Windows/Common/Threads.h
@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: MIT
+#pragma once
+
+namespace FEX::Windows {
+void SetupThreadHandlers();
+} // namespace FEX::Windows
diff --git a/Source/Windows/Common/WinAPI/IO.cpp b/Source/Windows/Common/WinAPI/IO.cpp
index b9e3359bf..ac960554a 100644
--- a/Source/Windows/Common/WinAPI/IO.cpp
+++ b/Source/Windows/Common/WinAPI/IO.cpp
@@ -111,10 +111,16 @@ DLLEXPORT_FUNC(HANDLE, CreateFileW,
 DLLEXPORT_FUNC(WINBOOL, WriteFile,
                (HANDLE hFile, const void* lpBuffer, DWORD nNumberOfBytesToWrite, LPDWORD lpNumberOfBytesWritten, LPOVERLAPPED lpOverlapped)) {
   IO_STATUS_BLOCK IOSB;
+  LARGE_INTEGER ByteOffset;
+  PLARGE_INTEGER ByteOffsetPtr = nullptr;
   if (lpOverlapped) {
-    UNIMPLEMENTED();
+    if (lpOverlapped->hEvent) {
+      UNIMPLEMENTED();
+    }
+    ByteOffset.QuadPart = (static_cast<LONGLONG>(lpOverlapped->OffsetHigh) << 32) | lpOverlapped->Offset;
+    ByteOffsetPtr = &ByteOffset;
   }
-  NTSTATUS Status = NtWriteFile(hFile, nullptr, nullptr, nullptr, &IOSB, lpBuffer, nNumberOfBytesToWrite, nullptr, nullptr);
+  NTSTATUS Status = NtWriteFile(hFile, nullptr, nullptr, nullptr, &IOSB, lpBuffer, nNumberOfBytesToWrite, ByteOffsetPtr, nullptr);
   if (lpNumberOfBytesWritten) {
     *lpNumberOfBytesWritten = static_cast<DWORD>(IOSB.Information);
   }
@@ -135,6 +141,18 @@ DLLEXPORT_FUNC(WINBOOL, WriteConsoleW,
   UNIMPLEMENTED();
 }
 
+DLLEXPORT_FUNC(WINBOOL, GetFileSizeEx, (HANDLE hFile, PLARGE_INTEGER lpFileSize)) {
+  IO_STATUS_BLOCK IOSB;
+  FILE_STANDARD_INFORMATION StandardInfo;
+  if (NTSTATUS Status = NtQueryInformationFile(hFile, &IOSB, &StandardInfo, sizeof(StandardInfo), FileStandardInformation); Status) {
+    return WinAPIReturn(Status);
+  }
+  if (lpFileSize) {
+    *lpFileSize = StandardInfo.EndOfFile;
+  }
+  return true;
+}
+
 DLLEXPORT_FUNC(WINBOOL, SetFilePointerEx, (HANDLE hFile, LARGE_INTEGER liDistanceToMove, PLARGE_INTEGER lpNewFilePointer, DWORD dwMoveMethod)) {
   IO_STATUS_BLOCK IOSB;
   FILE_POSITION_INFORMATION PositionInfo;
@@ -173,10 +191,17 @@ DLLEXPORT_FUNC(WINBOOL, SetFilePointerEx, (HANDLE hFile, LARGE_INTEGER liDistanc
 DLLEXPORT_FUNC(WINBOOL, ReadFile,
                (HANDLE hFile, void* lpBuffer, DWORD nNumberOfBytesToRead, LPDWORD lpNumberOfBytesRead, LPOVERLAPPED lpOverlapped)) {
   IO_STATUS_BLOCK IOSB;
+  LARGE_INTEGER ByteOffset;
+  PLARGE_INTEGER ByteOffsetPtr = nullptr;
   if (lpOverlapped) {
-    UNIMPLEMENTED();
+    if (lpOverlapped->hEvent) {
+      // no actual async-overlapped, just enough for PRead
+      UNIMPLEMENTED();
+    }
+    ByteOffset.QuadPart = (static_cast<LONGLONG>(lpOverlapped->OffsetHigh) << 32) | lpOverlapped->Offset;
+    ByteOffsetPtr = &ByteOffset;
   }
-  NTSTATUS Status = NtReadFile(hFile, nullptr, nullptr, nullptr, &IOSB, lpBuffer, nNumberOfBytesToRead, nullptr, nullptr);
+  NTSTATUS Status = NtReadFile(hFile, nullptr, nullptr, nullptr, &IOSB, lpBuffer, nNumberOfBytesToRead, ByteOffsetPtr, nullptr);
   if (lpNumberOfBytesRead) {
     *lpNumberOfBytesRead = static_cast<DWORD>(IOSB.Information);
   }
diff --git a/Source/Windows/WOW64/Module.cpp b/Source/Windows/WOW64/Module.cpp
index 75503c82d..2061bf061 100644
--- a/Source/Windows/WOW64/Module.cpp
+++ b/Source/Windows/WOW64/Module.cpp
@@ -38,6 +38,7 @@ $end_info$
 #include "Common/TSOHandlerConfig.h"
 #include "Common/ImageTracker.h"
 #include "Common/InvalidationTracker.h"
+#include "Common/Threads.h"
 #include "Common/OvercommitTracker.h"
 #include "Common/CPUFeatures.h"
 #include "Common/Logging.h"
@@ -515,6 +516,7 @@ public:
 
 void BTCpuProcessInit() {
   FEX::Windows::InitCRTProcess();
+  FEX::Windows::SetupThreadHandlers();
   const auto ExecutablePath = FEX::Windows::GetExecutableFilePath();
   const auto ExecutableName = FEX::Windows::BaseName(ExecutablePath);
   FEX::Config::LoadConfig(fextl::string {ExecutableName}, _environ, FEX::ReadPortabilityInformation());
diff --git a/Source/Windows/include/winternl.h b/Source/Windows/include/winternl.h
index 2ba99ba55..0244cb6b7 100644
--- a/Source/Windows/include/winternl.h
+++ b/Source/Windows/include/winternl.h
@@ -407,6 +407,23 @@ typedef enum _SECTION_INHERIT {
   ViewUnmap = 2,
 } SECTION_INHERIT;
 
+typedef NTSTATUS(WINAPI* PRTL_THREAD_START_ROUTINE)(void* Parameter);
+
+typedef struct _PS_ATTRIBUTE {
+  ULONG_PTR Attribute;
+  SIZE_T Size;
+  union {
+    ULONG_PTR Value;
+    void* ValuePtr;
+  };
+  PSIZE_T ReturnLength;
+} PS_ATTRIBUTE, *PPS_ATTRIBUTE;
+
+typedef struct _PS_ATTRIBUTE_LIST {
+  SIZE_T TotalLength;
+  PS_ATTRIBUTE Attributes[1];
+} PS_ATTRIBUTE_LIST, *PPS_ATTRIBUTE_LIST;
+
 /* definitions of bits in the Feature set for the x86 processors */
 #define CPU_FEATURE_VME 0x00000005    /* Virtual 86 Mode Extensions */
 #define CPU_FEATURE_TSC 0x00000002    /* Time Stamp Counter available */
@@ -518,6 +535,12 @@ NTSTATUS WINAPI NtAllocateVirtualMemoryEx(HANDLE, PVOID*, SIZE_T*, ULONG, ULONG,
 NTSTATUS WINAPI NtAllocateVirtualMemory(HANDLE, PVOID*, ULONG_PTR, SIZE_T*, ULONG, ULONG);
 NTSTATUS WINAPI NtContinue(PCONTEXT, BOOLEAN);
 NTSTATUS WINAPI NtCreateSection(HANDLE*, ACCESS_MASK, const OBJECT_ATTRIBUTES*, const LARGE_INTEGER*, ULONG, ULONG, HANDLE);
+#define THREAD_CREATE_FLAGS_SKIP_THREAD_ATTACH 0x00000002
+#define THREAD_CREATE_FLAGS_HIDE_FROM_DEBUGGER 0x00000004
+#define THREAD_CREATE_FLAGS_SKIP_LOADER_INIT 0x00000020
+#define THREAD_CREATE_FLAGS_BYPASS_PROCESS_FREEZE 0x00000040
+NTSTATUS WINAPI NtCreateThreadEx(HANDLE*, ACCESS_MASK, OBJECT_ATTRIBUTES*, HANDLE, PRTL_THREAD_START_ROUTINE, void*, ULONG, ULONG_PTR,
+                                 SIZE_T, SIZE_T, PPS_ATTRIBUTE_LIST);
 NTSTATUS WINAPI NtDelayExecution(BOOLEAN, const LARGE_INTEGER*);
 NTSTATUS WINAPI NtDuplicateObject(HANDLE, HANDLE, HANDLE, PHANDLE, ACCESS_MASK, ULONG, ULONG);
 NTSTATUS WINAPI NtFlushInstructionCache(HANDLE, LPCVOID, SIZE_T);
@@ -538,6 +561,7 @@ NTSTATUS WINAPI NtReadFile(HANDLE, HANDLE, PIO_APC_ROUTINE, PVOID, PIO_STATUS_BL
 NTSTATUS WINAPI NtSetContextThread(HANDLE, const CONTEXT*);
 NTSTATUS WINAPI NtSuspendThread(HANDLE, PULONG);
 NTSTATUS WINAPI NtTerminateProcess(HANDLE, LONG);
+NTSTATUS WINAPI NtTerminateThread(HANDLE, LONG);
 NTSTATUS WINAPI NtUnlockFile(HANDLE, PIO_STATUS_BLOCK, PLARGE_INTEGER, PLARGE_INTEGER, ULONG);
 NTSTATUS WINAPI NtWriteFile(HANDLE, HANDLE, PIO_APC_ROUTINE, PVOID, PIO_STATUS_BLOCK, const void*, ULONG, PLARGE_INTEGER, PULONG);
 void WINAPI ProcessPendingCrossProcessEmulatorWork();