(Closed your double post over in the bug tracker.)
Well, this seems like an issue with at least one of your mods.
Test them out, one by one and you'll eventually find out which one is causing the problem.
Enderal is already "heavily modded". It's not the real Skyrim.esm anymore, and some original Skyrim Scripts are also missing, so Skyrim mods won't work properly.
It could also be that your PC does get to it's limit. Skyrim is a 32 bit application, so it probably can't use all the ressources your PC might have.