[BUG] Opening/Closing tabs causes multi-second lag and CPU spike

[nomakewan]

Browser (please complete the following information):

• OS: Windows 7
• Version: 140.0.4-1
• This is a r3dfox specific bug: Yes (occurs in r3dfox 140.0.4, 140.0.4-1; occurs in FF-for-Win7 140.0.3; does not occur in FF-for-Win7 144.0a1)

Describe the bug
When a large number of tabs is restored for the active session (even when all but one tab are inactive), opening a new tab or closing any open tab causes the browser to lag for multiple seconds and a CPU spike.

To Reproduce
Steps to reproduce the behavior:

1. Start r3dfox with a profile that contains a large number of inactive tabs to restore.
2. Open a new tab or close an existing tab.

Expected behavior
New tab should open instantly or existing tab should close instantly.

Screenshots

Additional context
Using the exact same profile, this does not occur in Firefox Nightly 117, Firefox 115 ESR, r3dfox 128 ESR (though in that version hardware acceleration fails to work which made watching YouTube or Twitch streams painful), or Firefox for Windows 7 144.0a1. According to the profiler, the culprit is related to the RefreshDriver tick when recomputing the stylesheet.

[the-r3dacted]

Interesting, I think I've been dealing with this issue for a bit, but it also coincided with me switching to an older/slower system as my main so I chalked it up to decade old CPU being slow. Since it's in Firefox for Windows 7 140, but not 144, I assume the fix will get picked up as I work my way up the releases. I'm also curious if 140.2.0 ESR will have the issue when I get around to it.

Also 128 ESR has broken hardware acceleration?

[nomakewan]

Yes, I originally switched from Firefox 115 ESR to r3dfox 128 ESR in order to get the PIP volume controls back (I was spoiled by Nightly 117). But I noticed that YouTube and Twitch were insanely slow, and when I checked about:support I found that it was because the browser was not using hardware acceleration even though it was enabled in settings. Once I switched to r3dfox 140 the problem went away and now YouTube and Twitch work great, but the open/close tab issue is there.

It was also obvious that hardware acceleration was not working in 128 ESR because YouTube videos were less washed out than I'm used to (known issue when browser hardware acceleration is enabled).

[the-r3dacted]

But I noticed that YouTube and Twitch were insanely slow, and when I checked about:support I found that it was because the browser was not using hardware acceleration even though it was enabled in settings.

Odd, what hardware do you have? It shows as having hardware acceleration on my Quadro M2200.

It was also obvious that hardware acceleration was not working in 128 ESR because YouTube videos were less washed out than I'm used to (known issue when browser hardware acceleration is enabled).

Is it something like this?

[nomakewan]

Odd, what hardware do you have? It shows as having hardware acceleration on my Quadro M2200.

i7-4790K, 32GB RAM, GTX 1070, driver 475.14.

Is it something like this?

I had it set to "With the video player settings". I've changed it to match your setting and will see if that takes care of the colors, thanks!

[the-r3dacted]

I wonder if it's an issue with the modern driver, because my M2200 is fine in 128.12.0-rc2. I run 472.12 and I don't feel like upgrading to 475.14.

I can't test now or probably for a few weeks, but I could make a 4790K and GTX 1080 system with a fresh install of 7 and 475.14 to get the closest config to yours to test with.

[the-r3dacted]

Oh your reply made me completely forget what I was going to do lol. Here is a test build of r3dfox 141. I still want to make a few changes before I release it, but I would like to see if it fixes the issue or if it's still there.

https://litter.catbox.moe/9p83vo.zip

[nomakewan]

Oh your reply made me completely forget what I was going to do lol. Here is a test build of r3dfox 141. I still want to make a few changes before I release it, but I would like to see if it fixes the issue or if it's still there.

Still there.

Do want to thank you for the tip about the driver; just flipped between "With the video player settings" and manually setting 0-255 dynamic range and yes, that does indeed fix the washed-out video issue when it's manually overriding the dynamic range. Been living with that for probably over a decade, can't believe I never thought to try it.

[the-r3dacted]

Should be getting to 142 soon, and I want to try to make 143 beta and Plasmafox 144 alpha builds.

[the-r3dacted]

Another preview build, this time for 142

https://litter.catbox.moe/uw6601mirzj14rxr.7z

[nomakewan]

Another preview build, this time for 142

https://litter.catbox.moe/uw6601mirzj14rxr.7z

This build works perfectly!!! Smash hit, right on. No more massive CPU spike and multi-second lag when opening/closing new tabs even though I'm using the exact same profile. Also hardware acceleration is still working. Woohoo!!

EDIT: Just for completion's sake, one thing that does still take up CPU is dragging an open tab to reorder it in the tab list. But I actually don't recall if that was slow or not on the older browsers, so honestly not nearly as huge a deal as just opening/closing tabs. Right-clicking a tab and using "Move to End" actually happens almost instantly, so this particular lag is likely unrelated to the earlier issue and is instead something to do with the actual render engine or something like that (whatever is handling the "hovering tab" animation stuff).

[the-r3dacted]

EDIT: Just for completion's sake, one thing that does still take up CPU is dragging an open tab to reorder it in the tab list.

For some reason Windows Explorer sometimes does not like this for me and will make the computer super laggy. This behavior is ancient as I've traced it back to 10+ year old versions of Firefox. However I haven't gotten around to trying to trace it any further to find an exact version or commit as it's a bit finicky to get to occur.

Also can you test 140.2.0 ESR to see if it occurs there. If it does, I'll see if I can port the fix from 142 to 140.

[nomakewan]

Also can you test 140.2.0 ESR to see if it occurs there. If it does, I'll see if I can port the fix from 142 to 140.

Typing this on 140.2.0 ESR as we speak, close/open tab bug is still present.

[the-r3dacted]

If you have a Windows 10 VM or machine, can you test r3dfox 141 and Firefox 141 to see if it occurs there? Then if it's in stock Firefox 141, start testing 142 nightly builds until you find the first to work properly.

[nomakewan]

I do have a Win10 box but it's not this box; setting it up to do browser testing with this profile will take a bit. I should be able to get back to you on that tomorrow.

[nomakewan]

If you have a Windows 10 VM or machine, can you test r3dfox 141 and Firefox 141 to see if it occurs there? Then if it's in stock Firefox 141, start testing 142 nightly builds until you find the first to work properly.

The current release version of stock Firefox is 142.0.1, so that's what is installed on my Windows 10 rig. The bug with opening/closing tabs is not present, but the bug with the ridiculous CPU spike when dragging a tab around is present. r3dfox 141 has both the opening/closing tab CPU spike and the dragging-tab CPU spike on the Windows 10 rig. Both are using the same profile that I copied from my Windows 7 box.