Frame rate and Vsync issues

I've been playing this game since release but gave up on trying in more recent years since no matter what PC/laptop I play it on, I (and even friends) seem to be experiencing major frame rate issues.

In full screen mode the game will automatically turn the vsync off causing poor frame pacing.

In windowed mode, the vsync will remain on, but sometimes, it seems to be turning itself off temporarily or the frame rate seems to be dropping hugely for some reason.

I tried using Nvidia control panel and I think at some point tried all kinds of compatibility modes to fix it, but to no avail.

I also tried different FPS modes but none of them seem to work either. I haven't tried different resolutions however and normally play in x2 normal.

Does anyone have any ideas or solutions?