Windows 8/8.1/10 Graphics Lag

Hi! I had this fixed for a while, but it's back... My game gets choppy when there are a crap ton of people bossing. Cake boss in particular. I never DC or black screen, just a really bad frame rate.

I had this happen before at the Christmas boss, but I fixed it by turning off Compatibility mode entirely. Credits to Kimberly for that fix.

Well, I had to reinstall Windows recently and ever since, I've had a hard time with this despite using the same settings. I'm using the lowest graphics setting while cake bossing, using administrator mode, and ofc not using compatibility mode at all. Any ideas?