crazy amounts of lag spikes after playing for 30+ hours

ive been playing arc for a while and everything was fine, but as of about roughly a week ago ive been super laggy. i havent changed anything on my pc so i really have no clue whats happening. ive tried turning down graphics, preformance mode on, reinstalling, but nothing works and its been insufferable. i have ethernet, i have a pretty good pc, so im stuck. what do i do?