This seems to happen any time I use any modpack, but doesn't happen with the latest official Java snapshot on its own as far as I can tell, or any other application or game (using windows). Changing RAM allocation, Java version, driver/game settings doesn't seem to do anything, and I'm having difficulty even finding anybody else with this same issue.

Anybody know what causes this?

Edit:

mmmmmm

I got it running a lot better (still weird max frame spikes though, but 9ms instead of 30+) and all I did was..... turn on my headphones?