Yeah, I looked up info about my computer, and it looks like it's something to do with power saver mode. I'm getting 900 fps when it's plugged in, and 30 fps when it's on battery. Thank you all for verifying it's not my code.

I've written a gravity simulator, and it's been capped at 30 fps. I disabled t.window.vsync, which didn't help me, and then I read a forum page here on love.run, which gave some sample code which used love.run to run at 60 fps. I tried adding that in, and it fixed my problem for a little while, but ...