So I checked out the excess SSE stuff, but dealing with it is over my head in terms of editing.
There's a lot of extra poly around there, but I use Blender and it's having issues importing the files, as none of the texture files are with the material files, and all sorts of nodes are lining up or something. I don't know, Blender stuff, once I get it in an editable form I should be able to deal with it, but I can't load it on whatever soft-ware I have.
Shouldn't be a tough fix if it's just the excess stuff causing the lag, but I'm not even sure it's that. I have a (really stupid way I did it) Sky Orpheon (the WHOLE stage and re-texture + model import) plopped over a 3rd Transformation of Castle Siege with a massive Dragon-thing in the background and lava everywhere, ALL shoved out of view but still moving, and the stage works fine. LOL
This stage just has a bit of SSE mountain side, but not with much depth, and it's all static anyway.
It's probably the crazy lighting or pretty animations that are causing it.
At least, that's with my very little, completely lacking, negative zoned expertise.
I'll keep working at it though. I'll send it to good stage people too when I quit on it.