1.17.1 New caves incompatibility
new caves 2.2 https://www.curseforge.com/minecraft/mc-mods/new-caves/files/3372264
i cannot open an issue with them as they dont have a github. i do however have their discord server link.
Immersive portals version- 0.20

to reproduce open a world with new caves and immersive installed, and go to alternate 1 or alternate 2 and check your logs. it spams things and causes memory leak.
heres logs https://gist.github.com/drakosoldier298/f76a5a51759fe1f333073d31460691b8