Even though my monitor is set to 60 FPS, and Steam says the game is running at 60 FPS, the animations are slower than usual.

I overlayed the escape sequence of 1.2.5 and Linux, and got this.

Has anyone else encountered this before, and have a fix?

I have seen something similar before and it was when the ingame resolution of the meatboy window didn't have the appropriate refresh setting available in the monitor setting (as seen from xrandr). So looks like that

Couple things to try:

1. Try different resolutions for meatboy (720x480) should work at least according to xrandr

2. Try using fullscreen for meatboy

3. Try setting the refresh rate to 60hz in the monitor settings/ try a 60hz monitor (if you have one)

Using a resolution in Xrandr fixed the problem. Thank you.