Terminal Latency

I find the eventual conclusion baffling:<p><pre><code> &gt; Applying this custom tuning results in an average latency of 5.2 ms, which is 0.1 ms lower than xterm, and that’s with having a much more sane terminal without legacy cruft. </code></pre> This &quot;legacy cruft&quot; is as-close-as-it-gets compatibility to EVERYTHING the Terminal-based world has ever seen. It&#x27;s an asset, not a liability, for those who need it, in case they need it - and that could very well be <i>you</i> one day.<p>I find it quite amazing that xterm manages to more or less outperform all the other implementations while (probably - I have not actually verified) being he most complete and correct one. Thomas Dickey is the man!

I think this is important subject, but I&#x27;m always bit wary on pure software measurements; I feel like the Typometer data needs to be cross-validated against physical click-to-photon measurements. In similar vein focusing on specific millisecond values is of limited use when display updates are quantized to specific frame rates (i.e. 60Hz), so the main question is what percent of updates have 1,2,..n frames of latency. Of course I recognize that doing such measurements is immensely more effort, requires hardware etc, so I&#x27;m not berating author for not doing that.

I also recently tried different terminals, because I was annoyed by the startup time of konsole. I eventually settled for &quot;foot&quot; [0], which I think is a bit underappreciated. It would be an interesting addition for the benchmark, although it&#x27;s Wayland only.<p>[0] <a href="https:&#x2F;&#x2F;codeberg.org&#x2F;dnkl&#x2F;foot" rel="nofollow">https:&#x2F;&#x2F;codeberg.org&#x2F;dnkl&#x2F;foot</a>

A couple weeks ago I started noticing my terminal was weirdly slow to startup. I never understood why people cared about terminal latency until I had to wait literally several seconds after opening my terminal to start typing. I thought it was because I had installed oh my zsh and it was doing something funky at startup.<p>Looking into it more I realized that I had unthinkingly pasted an <i>echo &#x27;...&#x27; &gt;&gt; ~&#x2F;.zshrc</i> command into my .zshrc instead of running it on the command line. So every time I ran my terminal, it was not only running the same line hundreds of times, it was appending one more line.<p>I now appreciate a fast terminal startup much more after the experience.

The author links to a “blog post”, but hasn’t looked for much preceding work. For example, this article from 2018 in LWN was the first that opened my eyes to the wide differences in latency among terminal emulators:<p><a href="https:&#x2F;&#x2F;lwn.net&#x2F;Articles&#x2F;751763&#x2F;" rel="nofollow">https:&#x2F;&#x2F;lwn.net&#x2F;Articles&#x2F;751763&#x2F;</a>

Ghostty<p>I’m really interested in Mitchell Hashimoto (founder of Hashi Corp), terminal app he’s developing called Ghostty.<p>His latest blog post on it, also related to latency &amp; benchmarks comparable to Alacritty.<p><a href="https:&#x2F;&#x2F;mitchellh.com&#x2F;writing&#x2F;ghostty-devlog-006" rel="nofollow">https:&#x2F;&#x2F;mitchellh.com&#x2F;writing&#x2F;ghostty-devlog-006</a><p>For those interested in the tech, he’s developing it with Zig, uses SIMD extensively, and it’s cross platform. Can’t wait for him to launch it.

I ~am~ was interested in trying out alacritty after reading this, but they don&#x27;t seem to favour making it friendly to OS package managers. They don&#x27;t seem to be friendly to feature requests either, I see resistance to package managers and tabs. Its performance is quite good though.

As expected fine-tuned st is the clear winner. However, it can be improved even further by removing double buffering altogether. Since the code is very hackable it&#x27;s quiet easy to do and many LOCs can be thrown out.

I have a hard time believing that after this much effort benchmarking terminals and eventually having to switch to a different one that it wouldn&#x27;t have been easier--and a lot more constructive, not only for this one user but for society in general--just to contribute a fix to Xterm for whatever issue it is having with Unicode (which fwiw I guess hasn&#x27;t affected me yet, but if it ever does I&#x27;ll just fix it).

Have recently made the switch to Termius. I really like it. However, I noticed there is local lag when typing. Anyone else see this?

What is the use case for these latencies? Multi-player text gaming?

Ok... I&#x27;ll just say, 40 ms is fine.<p>Not if you are playing a game, or watching one of those text-art movies. But for normal terminal usage, as long as it&#x27;s constant, it&#x27;s just fine.

I have literally no idea why people care so much about typing latency. If you type that fast, I suggest that you seriously consider finding a more intellectually challenging task.