If not configured, the mod itself will encounter massive lag cause by mob path finding.
But when temp mob collision disable is set to true, player will suffocate upon climbing hills.
Is there really no way around?

I'm using NoCubes-1.20.1-0.5.0-dev-b81a6c5.jar
This is what happend:
https://github.com/Cadiboo/NoCubes/assets/28939939/759be80b-fae7-4556-99e6-d94a8651e385

What exact version of nocubes are you using?

The temporary workaround for the lag issue is tempMobCollisionsDisabled, which should not make the player suffocate. If this has not already been fixed in a newer version of the mod than you are using I’ll look into fixing this soon.

The next large update to the mod is aimed at fixing the performance issue with collisions.