To me, the most relevant aspect is the time it takes to open. I can't believe how slow the startup time in common linux distributions is by default, it's so annoying, by the time it opens I already forgot what I wanted to do. Alacritty has this cool feature where you only ever have to "open" a single terminal, whereas new windows can be created very efficiently with `alacritty msg create-window`, being forks of the initial window. It makes using my pc a lot more comfortable.

Speed itself may not be very important, but it is a very interesting challenge in itself - to prove to yourself that you can surpass the state of the art!

IME, usually you care more about latency than throughput for normal interactions, and there is a noticeable difference between the slowest ones, and the fastest ones, but I've tried a lot of terminal emulators, and any of the ones that put some effort into performance are plenty fast enough.

However, there is one case when throughput matters: when an application has a lot of output. But then the problem isn't the speed that it displays the text, it's going by too fast to read anyway, the problem is that the application can be slowed down by blocking on writing to stdout when the buffer is full. And honestly, the best approach in that case is probably not to actually render all the text, but send most of the output straight to the scrollback buffer, and only render some of the frames.

Terminal.app is amongst the best, if these old danluu benchmarks still hold https://danluu.com/term-latency/

the new Windows Terminal had horrendous performance when it first came out. in the aftermath of the drama surrounding that, was when I first started seeing a lot of terminal emulator projects bragging about their throughput.