I have a 2010 Macbook Pro. I can't hang with the last version of Firestorm either. I have been using Singularity now for several months and I like it.
Regarding the overheating issue ... never use a MBP on your lap, a pillow, or anything soft. Get a coolpad or coolermaster or something else with a fan that will cool your MBP especially in warmer (80 degrees ... not that I remember what that feels like any more) weather.
I have never "fried" a MBP in all the years I have been in SL ... and I am talking about HOURS and HOURS online.