[swdunlop]

I have found that fan will run like crazy even with htop showing low CPU usage. It is something about Thunderbolt that seems to produce substantial waste heat, even when it's just a single terminal watching htop.

Driving one or two displays doesn't have a perceptible difference for me; I wouldn't want to play a Steam game that way, but watching Hulu or Netflix on one screen while I code on the other doesn't impact Sublime Text's performance. :)