Low fps after playing for more than 20 minutes/loading multiple times

hi there. so it seems to be if i restart a level or reload saves a few times at a some point fps will drop to 10-20 and i can’t figure out why. i suspect it’s from the cpu or ram maxing out but i have only been having this issue since the last update, before it i never had problems maintaining 40+ fps on any level, legacy or h2. drivers are all up to date, gpu: gtx960, cpu: i7-4770K @ 3.50GHz, 16gb ram. i can’t think of anything that has changed since it was working fine other than the last update but maybe i’m mistaken. not really sure how to go about fixing it so any help would be appreciated.