I have similar issue with Intel GPU and window mode, but not with fullscreen mode or NVIDIA GPU.
Intel GPUs emulate vsync in window mode using Sleep(), which is affected by Window’s timer resolution.
Windows’s default timer resolution is 15.6ms and that shouldn’t be enough to emulate vsync.
Tested with “next” version of OpenFL.
Next Lime always uses timer to wait for 16ms, whether vsync is enabled or not. I think this is problematic, too. If vsync is not enabled, that should make FPS 62.5, not 60.
Lime is using SDL’s timer internally.
I suppose SDL_Timer uses QueryPerformanceCounter on windows, so this is not affected by timer resolution. QueryPerformanceCounter may not work correctly in all situations, though.
Game Timing and Multicore Processors (Windows)