I do have a lot of downloads, about a couple hundred. And also I have a new Mac.
I would Take ALL your Mods out, and start the game. If it loads nice and fast... well there you go!. I know with Sims 2. when I had about 18 gigs of DL it took about 2 hrs to load.... I learned to have a more discerning eye when it came to things i just HAD to have! I now have about 100 downloads in my game lol.