itch.io

Really odd. I'll investigate. Alt-tabbing from the game can mess it up, but I don't think that's the case. Thanks for the report.

So I did some research, and it seems like this is a dumb GameMaker engine-side issue, but luckily there's a PC-side fix:

https://forum.yoyogames.com/index.php?threads/solved-game-not-running-at-60-fps-...