Does anyone happen to know if running too many mods at once can cause excess lag? Most of the mods I run are new items or companions. I don't use any of those fancy mods that require things like FOSE. I just wanted to know so that I don't download too many. Thanks in advance.

It depends on what the mods are. A few items and companions wont do much, but when you get a lot of items, NPCs, scripts, or high res textures going, you can see some lag.

You really don't have too much to worry about.

It also depends on your system. If yours is on the low end, either your CPU or video card, then yes. But if you have a fairly good system then you shouldn't have any problems.

General rule of thumb, bigger the scope of the mod the bigger the hit on performance. Alone its generally negligible but when you have a lot (read 50 - 100+) you can start to see a 5-10+ fps hit. And as with everything it varies by computer.