Game capped at 30fps whilst v-sync disabled

This bug has occurred consistently for the last year or so and every time I play the game it would switch between 30fps and 60fps. I would go from 60fps and randomly cap down to 30fps and if I alt-tabbed out of the game and back in it would switch to 60 occassionally, then moments later, it switches back to 30fps. This makes no sense whatsoever. I have tried following advice from people such as disabling v-sync in my nvidia settings as enabling tripple-buffering, none of it works. Disabling my mods did not work as well.