Dash-to-panel: Issue #310 appearing again; Lag after moving mouse rapidly over app icons

[lckjosh]

Sadly I experience this again, whole system animations and even glxgears start to become choppy. However, disabling window previews on hovering over icons seems to fix the issue.

[lckjosh]

Also, can I add a feature suggestion, which is to add "show window previews" as an opton under "click action"? That would essentially solve the problem for me personally.

[charlesg99]

Could you please provide your distro/gnome-shell version? Also, for it to happen, does the window preview popup menu needs to appear or do you only have to move the mouse rapidly over the icons? I would like to try to fix that, but I can't reproduce it here (arch, gnome-shell 3.26.2). Thanks

[lckjosh]

Sure. Here are my system specs too, just in case.
OS: Ubuntu 17.10
Gnome 3.26.2
CPU: i3-4170
GPU: Radeon R7 250
RAM: 8GB DDR3

I think the window has to appear, it will anyway when I move my mouse over the icons. The choppy animations don't appear immediately though, it gets worse over time.

Here's a video showing the difference between the smooth and choppy animations: https://youtu.be/nMNmI0XgWC4

[lckjosh]

Update: It seems like this issue has been reported before in issue #186
A recent reddit thread https://www.reddit.com/r/gnome/comments/7teono/possible_fix_to_improve_gnome_lag/ has also mentioned this.

[LiamDawe]

I've been experience a really "laggy" system for the last few days, disabled Dash to Panel and suddenly it's golden again.

Something in the extension is causing huge system slowdowns for me.

[charlesg99]

@LiamDawe Do you experience the same problem as Ickjosh (slow down over time with the window previews enabled)? When you see the lag, what is the gnome-shell process cpu usage like? Could you also please provide some more information on your system? Dash to panel settings, distro, system specs, gnome-shell version, xorg or wayland. Thanks

[TechnoSparks]

I used to also have this lag overtime that I even decided to distro hop to Budgie. However, the change was not feasible and I had to come back to Gnome. Gnome and Dash to Panel really rocks. I didn't think that Dash to Panel was the reason behind the lag because i was too frustrated, but I will definitely keep an eye to this. Will report findings later since I was just clean reinstalled my distro.

Also, i would also vouch for the suggestion in the second post. Would be better if an option for window previews could be disabled but only leave text items to click on.

[charlesg99]

Hey @TechnoSparks, sounds good, I really would love to be able to reproduce it reliably. I'm using dash to panel for long periods without problems, but I did experience this lag 2-3 times. Pretty sure it wasn't "over time" also as, for me, it seems to have happened all of a sudden.

[TechnoSparks]

I see @charlesg99 . But I have a very contradicting finding here.

Unfortunately, window previews for Dash to Panel is not the cause of the lag, so my issue is completely unrelated with this specific GitHub issue…

I have also disabled window previews in ALT TAB switcher by modifying options for Alternate Tab extension to see if it was to blame. However, the answer is “no” too.

As to the true cause of the “over time” lag, that is still a mystery. I have tried to disable one extension at a time to see the offending extension (except Dash to Panel. Will do it after a test that I will explain in the next sentence) — but those extensions are not to blame. If anyone wants to hear something positive, I have disabled Dash to Panel’s “Show AppMenu Button” and “Application Menu” in Tweak Tools. I am currently experiencing no “over time” lag, but it is still too early to say so. I need more time (possibly days) to confirm if this may be the cause to my lag.

I’d suggest other affected users to try the same.

Side note:
When experiencing the lag, disabling or enabling any extensions in tweak tool will restore the shell’s performance, albeit temporarily.

[charlesg99]

@TechnoSparks When you say "over time", are you talking minutes or hours? Thanks

[TechnoSparks]

@charlesg99 I need to use the desktop productively and then the issue will appear roughly after 30-40 minutes. If i instead leave the machine idling, the lag doesn’t happen.

---

Disabling AppMenu seemed to not fixing it. I have now disabled launching and switching animations under “Fine Tune” tab of Dash to Panel settings.

I am preparing to use Gnome without Dash to Panel as a final experiment, if and only if my previous test yield a negative result.

[TechnoSparks]

Seems to be an issue of Gnome after all. In light of this post on omgubuntu which now publicised the shell lag issue.

Funny is that my machine is running 8GB of RAM, and the effects still appear prominent despite the shell haven't yet crossed 500MB mark, at least for my machine.

[TechnoSparks]

Hello I am back to report that yes, the original description of the issue is the true replication method. @charlesg99
Animations started to stutter after moving my cursor on the favourite (running) icons on the panel. I moved the cursor quite fast, but not too fast so that the window preview may appear briefly.

Unique to me however, the stutter decreases after a while, but still retain a little stutter. I dont know if this relates to my issue ranted above, but I will definitely test that out later and will create a new Issue if required.

[TechnoSparks]

I can now confirm the source of the stuttering is caused by "Show window previews on hover".

[sgmihai]

Can confirm the same. Turning off window previews fixes the lag. Randomly turning on/off extensions temporarily fiexes it, for some while. This has been bugging me for 3 days since I installed the extension.
Manjaro Linux, Kernel 4.18, Vega 64, Gnome 3.28.3/Wayland.
Please fix so this wonderful extension can be perfect.

[TechnoSparks]

Greetings @sgmihai, do you use an SSD?

[sgmihai]

@TechnoSparks yes I do, Samsung NVME

[TechnoSparks]

@sgmihai Hm. I just upgraded to Sandisk Ultra, although SATA link. The problem seemed to be have gone (I tried to replicate the bug), but I also have updated to v16 (so I am not so sure if v16 fixes it, or the SSD fixes it, or other combination(s)). Have you also updated?

Nope nope, never mind, issue persists!

[TechnoSparks]

My theory is that Dash to Panel may have an aggressive caching of the window thumbnails, thus may explain why this stuttering appears after a while and not instantaneously. Although I can read js, I unfortunately cannot _read_ Gnome extension. I think, if we could provide a way to disable window thumbnail (just show text like Windows (OS) do if thumbnails disabled), this could be a great workaround for us unfortunates who have this animation stutter.

_Source: https://helpdeskgeek.com/how-to/disable-taskbar-thumbnail-previews-windows/_

The developers have least interest on this bug, but we cannot blame them either as they are unable to replicate the bug. I will try to get my hands dirty for mentioned workaround in the meantime (maybe after Gnome 3.30 dropped in Manjaro testing). No promises though.

[jderose9]

@TechnoSparks You may disable window previews by turning off Show window previews on hover on the Behavior tab of the settings.

I certainly have interest in resolving this problem, but it is not clear to me what is causing the problem, and I have never been able to reproduce it, on a variety of hardware and Virtual Machine settings.

Still, if you are willing to test, I can attempt different strategies for creating/cleaning up the live preview, or possibly using a static snapshot of the window rather than a live preview, and see if you have any improvement.

Thanks!

[TechnoSparks]

@jderose9 Yes, I have disabled it for so long. Just that sometimes I enable it for the sake of trying to track the true cause of the animation stutter. Of course, as of now, still no avail…

I am definitely interested and willing to test anything that you can come up with.

Oh, I need to emphasise on one particular behaviour of the panel: To make the animation stutter come earlier, one need to hover the active tasks' icons on the panel until the preview appears, then proceed to another icon, back and forth. The more the apps running and you did this, the quicker the issue appears.
_How to_

Completely speculative: it could be that each hover spawns a listener(?) that updates based on the window state, and if hovered repeatedly, duplicate numbers of listeners exists and bring down the performance of the shell. (whew that is weird speculation, but hey, I am trying my best 😅)

Anyway, I am really interested in testing. Just reply to this issue and I will be right on my way!

[TechnoSparks]

Issue disappeared in Gnome 3.30. Could be upstream issue after all?

Anyway I am extremely happy the bug flew away!

[charlesg99]

Hello, closing for now as the issue is related to the previous window previews. Please install the latest master and reopen the issue if the lag persists with the new version of the previews! Thanks!