Extreme FPS drop, thermal expansion the problem?

[DiscoDino13]

I been working on a world forever to get it ready to play in with friends but all of sudden the FPS dropped and I can't really move and I can access anything but the menu options. I been looking everywhere on the forums and can't exactly find anything that helps. I had to quiet and saw there was a crash report and I'm hoping it will help. I took a screenshot of it so it won't be annoying long thread. I made a back up of my world and I tried to find out to load a later saved version of the world too. But nothing is really helping or giving direction on how to fix this. I'm also on a mac os x yosemite too. 

Edited December 8, 2015 by DiscoDino13