Low fps on my main world

[Rohan boi]

So lately I started noticing stutters and fps in my main world all of a sudden . I have a decent pc and changing graphics low to epic I get same fps around 80 and drops to 50 . My gpu usage was around 60-70% and cpu 25% . Tried everything nothing worked . Created another world and I’m getting 120fps on epic with all same settings even world settings. On low I get 250fps and point is my gpu was at 100%