There’s been a bit of a mini-fad of late on the internet of programs that create a full-screen window with text only, very much like the bad old days of 80×25 phospor. I think it started with Dark Room, but I could be wrong. There are several others.
The idea has some merit, but for the coding and hacking I do the closest thing I’ve found is a Linux console: There, you have eight terminals instantly switchable with alt-Fn. My home server never runs X for this very reason; I have enough superfast terminal windows for anything I want to do.
The latest release of the FOSS iTerm adds this capability to my Mac. By hitting apple-enter, you enter or leave full-screen mode. Apple-T still gives a new (also full-screen) terminal, and most importantly I can switch between them with apple-number (e.g. apple-1). I had tried iTerm a few times before and hadn’t liked it due to some lagginess on keyboard, that’s also now fixed and I’ve stopped using Terminal.
(For me, that’s a huge thing. Really.)
Fast. No distractions, works well, is free. Highly recommended.