As far as I understand, socialCache has to do with SimPort and maybe some other social features, like gifting. Maybe this is a known issue (™) and someone will have a simple solution, but if not, a bit of testing might help. What happens if you don't login at either the launcher or Main Menu, or even further, if you take your computer entirely offline (disable wifi and/or pull the ethernet cable) before launching TS3? What if you pull your entire TS3 game folder out of Documents\EA and then try to start a new save?
Also, for what it's worth, my simCompositorCache from the last time I properly played is even bigger: 289.4 MB; compositorCache is 44.7 MB. So (I delete them every time I quit as well.) I'm not sure that the size of the cache alone is the cause of the crashing, although it could certainly be a symptom. It would be interesting to see whether you can get socialCache to stay smaller, and whether your existing save loads.
