I did try ITerm2 out for a long time but I found it dramatically reduced the battery life of (newish) macbook, I'd get perhaps 2 hours less per charge, as a res

I did try ITerm2 out for a long time but I found it dramatically reduced the battery life of (newish) macbook, I'd get perhaps 2 hours less per charge, as a result i've switched back to Terminal and using MouseTerm for scrolling in vim. Have you looked into ITerms' performance in comparison to Terminal?