I've just tried it on 2014 MacBook Pro with Intel Iris GPU. It seems it bit more sluggish than the built in Terminal app.

No hard numbers, yet simply resizing a window is visibly slow or "accidentally" catting 100k line txt file in the terminal takes several seconds. Both is instant in iTerm and Terminal on my machine.

Isn't Apple's terminal already GPU-rendered too? Or was that iTerm2…

iTerm2 can be (it's configurable). Not sure about Terminal.