I have no idea why it was. Yosemite(w/Webkit) maybe have a bug about awaken?
So this is the process that actually runs the js. It might be stuck in a loop. I try to avoid this (for example by disallowing while) but there are still ways to do it like calling Utils.interval with a delay of 0.
The good news is that you can just force quit that process in activity monitor and refresh in Framer Studio. It will all work again. Just remember that if you had JS causing the issue and you didn't fix it, it will likely trip out again.
Its Apple wanting you to use Quartz Composer instead of Framer :D