Still doing it after that as well
In case it's helpful, here's the stack of the busiest thread in the process courtesy of Process Explorer:
ntoskrnl.exe!memset+0x64a
ntoskrnl.exe!HalPrivateDispatchTable+0x1160
ntoskrnl.exe!__misaligned_access+0x1821
ntoskrnl.exe!KiCheckForKernelApcDelivery+0x25
ntoskrnl.exe!KeSetActualBasePriorityThread+0xc6b
win32k.sys!EngCopyBits+0x1684
ntoskrnl.exe!KeSynchronizeExecution+0x3a43
wow64win.dll+0x4007a
wow64win.dll+0x1beb3
wow64.dll!Wow64SystemServiceEx+0xd7
wow64cpu.dll!TurboDispatchJumpAddressEnd+0x2d
wow64.dll!Wow64SystemServiceEx+0x1ce
wow64.dll!Wow64LdrpInitialize+0x429
ntdll.dll!RtlUniform+0x6e6
ntdll.dll!RtlCreateTagHeap+0xa7
ntdll.dll!LdrInitializeThunk+0xe
USER32.dll!GetDC+0x177
SDL.dll!SDL_RegisterApp+0x2a29
SDL.dll!SDL_PumpEvents+0x22
SDL.dll!SDL_PollEvent+0xb
Amnesia.exe+0x1ac8f2
Amnesia.exe+0x11942c