I have all the expansion and game packs, a couple of the stuff packs and about 800 mods, most of which is cc but some script/core mods. I have a mid range pc and haven't really experienced any slow down and no freezing. The few glitches I've had have been fixed by clearing out the caches etc.
If you are worried then start small with a few pieces of cc and create a new save the test them. Add a few mods and test again in that new save and if there are no problems then start using in your main games.
I get most of my mods from Mod the Sims and they make it easy to check if they are up to date.