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Comment by deng | Hacker News Reader

All these latencies are well below 50ms worst-case. For me, those are perfectly fine for typing. While it is obvious that high latencies have an adverse affect on typing, there certainly is a "good enough" threshold. I find it very hard to believe that you'd be able to see any difference in typing with 2ms and 20ms latency. The article even implies that terminals with higher latency might cause RSI, which is damn close to fearmongering. The article also claims that the GNOME Human Interface Guidelines require 10ms latency, while clicking that link shows "0.1s", which is much more reasonable. And just to be clear: I'm strictly talking about typing. I do not question that in other areas latencies have to be much lower than 50ms (like mouse movement, music making, etc.).

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Latency, as the article points out, is less of an issue than jitter.

Consider that 80wpm is right around 60ms a keystroke. 50ms jitter will have some keystrokes arriving twice as slowly as others. I suspect that's a noticeable difference; indeed, I suspect I've been noticing it for decades now.

Agreed. Where its inconsistent, I personally find myself working harder to manage the stream of input.

I definitely can feel the lag in normal usage, and it's stressing me. Having tried various terms, I've always quickly returned to xterm with bitmap fonts - even before I'd heard of latency measurements being done on terminal emulators. xterm feels almost instantaneous. Gnome Terminal, for example, always felt sluggish. Not having done any measurements I couldn't tell what it was (and didn't think that other terminals could possibly have noticeably slower latency) - and I still think there can be other contributing factors, like usage of Vector fonts and aliasing. Or, as someone else points out, it might be more jitter than lag.

I also never liked GNOME 3, and suspected it must have something to do with it being a compositing WM and the latency it probably adds on top.

Between Windows, macOS, and the major Linux desktop environments, practically no one is using a non-composited desktop these days.

Compositors tend to aim for 60fps, because that's what most displays can handle. That means you _start_ with 16ms worst case latency on the output side.

You can use one of the many bare-bones window managers to get rid of compositing. I still use xdm and only recently switched away from icewm (because of bitrot) to openbox.

The physical display is still 60 fps. Frankly, CRT displays used to be only 60-80 fps.

I still think that there are much longer (and noticeable) delays in the terminal emulators themselves, dwarfing the compositing and display delays.

So am I the only one left without compositing WM?

Here I am too. I stick to dwm, currently migrating to wmutils because portability, no compositing on my side. Firefox is the only GUI program I use (besides st), and it will probably remain as such since the web has become a chaotic and complex environment, unusable without a major web-browser.

While I agree with most of what you put here, the idea that higher latencies may contribute to RSI is plausible.

A while back, I was showing symptoms. It turns out, that I was tensing during periods of waiting to see feedback. Now, being aware of it, it's no big deal, and I don't do it anymore. Symptoms gone.

Yes, it is plausible for latencies in the range of >100ms, but not for the ones shown in the article.

You don't think someone with a pretty rapid response time couldn't tense and relax?

They may just do it when the latency varies.

You mean you hit key "a", and while waiting 50ms for it to appear you tense up? No, I don't find that likely.

For one key, in isolation, agreed, not likely.

However, for a string of them? Yeah, could be a factor. My own trigger was mere awareness.

Just knowing it couldbe latent to excess triggered that tensing, like "stay ready."

All I'm saying is its plausible. People can, do, will respond very differently to these kinds of things. Worth investigation.

For typing I doubt it, ideally you should be able to type fine if the display only updated every 10 seconds.

For i.e. the arrow keys, or anything interactive you will probably have to be watching for the response.

Agreed. Another example would be gaming with the keyboard - latencies are surely much more noticeable here. I would guess it is similar to music making, where you strive for latencies <10ms.

As a gamer, I wonder how noticeable this latency truly is (2ms - 50ms). The browser runs at "60fps" so any input, by default has a 16ms delay (unless I'm understanding the browser incorrectly). This kind of delay does not phase me one bit. However, if it was 3 frames (ie. ~50ms), how much would that bother me?

Lands right in the "sees last char input hit the screen as next one is being, or about to be typed" range, depending on typing speed.

50ms = 0.05s = 1/20s

Are you sure you're typing 20 letters per second?

No, not often. For some common words yes. Depends on keyboard at that point. Some will take it, some won't.

In game terms, input can approach that speed, which is really what I was writing to. Should have said, by analogy.

For me, a whole lot depends. If I am transcribing, I look at the screen, and it can matter. Same for a quick type of a common phrase. I'll blast that out.

For most things, it's a few CPS and slower.

And this is all modal. Interactive, like cursor navigation is different from general character input, which is different from common, short words.

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