diff --git a/UnleashedRecomp/app.cpp b/UnleashedRecomp/app.cpp
index f209836..c4b6a32 100644
--- a/UnleashedRecomp/app.cpp
+++ b/UnleashedRecomp/app.cpp
@@ -35,6 +35,8 @@ PPC_FUNC(sub_824EB490)
     __imp__sub_824EB490(ctx, base);
 }
 
+static std::thread::id g_mainThreadId = std::this_thread::get_id();
+
 // CApplication::Update
 PPC_FUNC_IMPL(__imp__sub_822C1130);
 PPC_FUNC(sub_822C1130)
@@ -51,8 +53,15 @@ PPC_FUNC(sub_822C1130)
 
     App::s_deltaTime = ctx.f1.f64;
 
-    SDL_PumpEvents();
-    SDL_FlushEvents(SDL_FIRSTEVENT, SDL_LASTEVENT);
+    // This function can also be called by the loading thread,
+    // which SDL does not like. To prevent the OS from thinking
+    // the process is unresponsive, we will flush while waiting
+    // for the pipelines to finish compiling in video.cpp.
+    if (std::this_thread::get_id() == g_mainThreadId)
+    {
+        SDL_PumpEvents();
+        SDL_FlushEvents(SDL_FIRSTEVENT, SDL_LASTEVENT);
+    }
 
     GameWindow::Update();
     AudioPatches::Update(App::s_deltaTime);
diff --git a/UnleashedRecomp/gpu/video.cpp b/UnleashedRecomp/gpu/video.cpp
index 338ff95..78e4d09 100644
--- a/UnleashedRecomp/gpu/video.cpp
+++ b/UnleashedRecomp/gpu/video.cpp
@@ -562,7 +562,6 @@ static void DestructTempResources()
     g_tempBuffers[g_frame].clear();
 }
 
-static std::thread::id g_mainThreadId;
 static std::thread::id g_presentThreadId = std::this_thread::get_id();
 
 PPC_FUNC_IMPL(__imp__sub_824ECA00);
@@ -1482,8 +1481,6 @@ void Video::CreateHostDevice(const char *sdlVideoDriver)
     for (auto& renderSemaphore : g_renderSemaphores)
         renderSemaphore = g_device->createCommandSemaphore();
 
-    g_mainThreadId = std::this_thread::get_id();
-
     RenderPipelineLayoutBuilder pipelineLayoutBuilder;
     pipelineLayoutBuilder.begin(false, true);
     
@@ -1742,6 +1739,8 @@ static void LockTextureRect(GuestTexture* texture, uint32_t, GuestLockedRect* lo
 
 static void UnlockTextureRect(GuestTexture* texture) 
 {
+    assert(std::this_thread::get_id() == g_presentThreadId);
+
     RenderCommand cmd;
     cmd.type = RenderCommandType::UnlockTextureRect;
     cmd.unlockTextureRect.texture = texture;
@@ -5540,14 +5539,27 @@ static void CompileParticleMaterialPipeline(const Hedgehog::Sparkle::CParticleMa
     }
 }
 
+#ifdef _DEBUG
+static std::thread::id g_mainThreadId = std::this_thread::get_id();
+#endif
+
 // SWA::CGameModeStage::ExitLoading
 PPC_FUNC_IMPL(__imp__sub_825369A0);
 PPC_FUNC(sub_825369A0)
 {
+    assert(std::this_thread::get_id() == g_mainThreadId);
+
     // Wait for pipeline compilations to finish.
     uint32_t value;
     while ((value = g_compilingDataCount.load()) != 0)
+    {
+        // Pump SDL events to prevent the OS
+        // from thinking the process is unresponsive.
+        SDL_PumpEvents();
+        SDL_FlushEvents(SDL_FIRSTEVENT, SDL_LASTEVENT);
+
         g_compilingDataCount.wait(value);
+    }
 
     __imp__sub_825369A0(ctx, base);
 }