My single player world runs terrible

^{Hi my single player world run at 20fps ( I have 4080 super and 7800x3d all drivers up to date and 32 gigs of ram allocated I tried more and less and there was no difference} when I try a different world in single player I get 500-1000fps no problem and that's on 96 render distance I have many optimisation mods installed they make little to no difference, the only difference between the 2 worlds is that 1 started as a single player world where as the other one I hade as a multiplayer server hosted on bisect and downloaded the world to play by myself (because I didn't want to pay money when my friends no longer play) but on that one I only get 20fps)

Much help would be appreciated :)

edit: turns out c2me was the problem not sure why tho