https://sureai.net/forum/viewtopic.php?t=3674
Casper wrote:nehrim does crash somewhat frequently on my rig (run of the mill CTDs); however, it seems to run more smoothly than oblivion itself. talking about lag, spellcasting (with distant lands enabled) does cause a bit when i'm in the dark forest, and in the southlands crater, using lightning spells doesn't seem to increase lag though (as far as i can tell). my guess is the particle effects from spellcasting have something to do with it as well, assuming my observation holds up.
as for the dark forest i figured it was all the light sources & that illuminated fog stuff, there is a bit of that around the crater too.