It's probably what ninjin said -- XQuartz latency. I use it on Debian, and speed-wise, I can't tell the difference between st & the GPU-accelerated terminals.

It's probably what ninjin said -- XQuartz latency. I use it on Debian, and speed-wise, I can't tell the difference between st & the GPU-accelerated terminals. On Mac, I switched from iTerm2 to Apple's built-in terminal. It sips battery compared to all of the others.