On: Kitty – a fast, featureful, GPU based terminal emu...

[dancek]

Input latency makes for a bad user experience. People just usually don't notice it when typing as it's so common. See https://danluu.com/term-latency/ for measurements of some terminal software and discussion of why latency is bad.

I'm not sure if Kitty is using GPU specifically to minimize latency, but it would be a good reason.

[simias → dancek]

I work in video and as a consequence I tend to be very sensitive to latency (I've spent more hours than I can count trying to figure out subtle synchronization issues) yet I've just spent one minute trying to detect input latency on my st terminal (which fares pretty badly in the benchmark you linked) without success. And that's running inside tmux on top of that.

That being said I think it is valuable to have a reasonably fast terminal because it's not uncommon to have applications slow down dramatically if they output a lot of information on stdout/stderr while the terminal struggles to render everything.

[matt4077 → simias]

I would have said the same, until I recently had to boot into an UEFI shell.

Input was just so .... immediate? It’s really hard to describe, but it was surprisingly obviou.

[dancek → matt4077]

Yeah, the feeling is pretty much "the letter appears while I'm pushing the key down" vs. "the letter appears when the key returns to the top position". Both feel immediate in their own way.

[heavenlyblue → simias]

I don't know. Try using a simple, $2 (physical) calculator against the screen of your computer.

I can definitely tell you that while I can't see the actual letter appearing on the screen - the letter on the calculator would feel as if it appeared right at the bottom position of the button, while on my PC the key would have travelled some distance off the ground before I see the letter.

It's not uncomfortable, but I could easily tell the two apart in a blind test would something like that come up.

[bergesenha → simias]

From what I can gather from the results, st is among the faster ones when tested on linux.

[IshKebab → dancek]

I would have thought using a GPU would make latency worse. GPUs are really good at throughput, not latency.

[tpolzer → dancek]

Usually, offloading to the GPU will get you higher throughout but also higher latency. Although of course this assumes a sane software renderer, X11 API calls will take forever.

[dancek → tpolzer]

Really? It's counterintuitive considering the GPU draws the screen anyway. Is it because the shader pipeline has some inherent latency that a software renderer doesn't?

[snvzz → dancek]

>There are no benchmarks in which I've found Alacritty to be slower.

It's depressing that he's only ever tried for throughput, when that's irrelevant next to latency. And it does have abysmal latency as per your link.