Closing a large number of tabs & windows with tab center enabled hangs the browser

[mystor]

Profile: https://perfht.ml/2pbpbRj (sorry it's not symbolicated - I had to use GDB to dump the profile as the browser completely hung up and wouldn't let me resume control).

It looks like we're spending a lot of time in https://github.com/bwinton/TabCenter/blob/caf419af625d200fc1e665cd5167695280bc528f/verticaltabs.js#L465 which makes me think that that line of code is triggering a lot of style recomputation or similar.

To reproduce this, I was on linux and had tabcenter enabled and a large number of windows opened. I used https://addons.mozilla.org/en-US/firefox/addon/close-other-windows/ to close all of my tabs very quickly and then my browser hung for multiple minutes. I had to use gdb to get the profile stack. The content process appeared to be operating fine, although the chrome was completely unresponsive.

[grahamperrin]

Here: Firefox on TrueOS Desktop (FreeBSD-CURRENT).

… https://addons.mozilla.org/en-US/firefox/addon/close-other-windows/ to close all of my tabs very quickly

I tried that approach a few times (less than ten) with version 0.1 of the extension, Firefox probably 53.0.2 at the time. At least one of the attempts was with Tab Centre disabled. Use of the extension seemed likely to crash Firefox, which is extremely unusual on FreeBSD (YMMV).

Now with Tab Centre enabled, I'll try that extension once more …

and then my browser hung for multiple minutes. …

I'd half-expect that (here, at quit time the Firefox process typically runs for a few minutes after all windows close … not a complaint, I guess it's because my 'everyday' profile is heavily extended).

[grahamperrin]

@mystor would you like me to use https://github.com/mystor/close-other-tabs for an issue with your Close Other Windows extension?

[mystor]

@grahamperrin Sure.

[grahamperrin]

https://bugzilla.mozilla.org/show_bug.cgi?id=1373822#c4 under Mozilla bug 1373822 - Lag when closing tabs refers to Tab closing became very slow in today's nightly · Issue #598 · mozilla/testpilot-containers

[grahamperrin]

Please: with release 56.0 of Firefox, is this still an issue?

[bwinton]

Given that TabCenter doesn't work on 56, I'm going to say no, or at least, we're not going to fix it. 😉

Thanks for the report, though!

[grahamperrin]

(Oops! Sorry for the carelessness. I forgot about the explicit incompatibility. A couple of weeks ago I loosely thought of this issue whilst thinking more broadly of performance-related issues elsewhere.)