1677393 - YouTube causes Firefox to be unresponsive for intermittent periods of time

Status: RESOLVED WORKSFORME

(Core :: Performance, defect)

Description

[saikogekido]

Attachment: firefox_kFa1wqhBll.png

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:84.0) Gecko/20100101 Firefox/84.0

Steps to reproduce:

Navigate to YouTube.com

or

Click a link to a youtube video

Actual results:

Entire application hangs for up to 30 seconds.
CPU usage maxes out.
Inputs are delayed, but can be queued (e.g. if you click multiple things during the hang, it won't respond for a few seconds, but when it does it will perform all of those clicks in the order you clicked them).

Expected results:

Video should load shortly. The application should be responsive during that period of time.

Comment 1

[saikogekido]

Attachment: youtube_console_logs

Here are the console logs from that screenshot.

Comment 2

[saikogekido]

Here are the console logs from that screenshot.

Comment 3

[saikogekido]

Also my system specs are:

• Windows 10 Version 2004
• Nightly 84.0a1
• AMD FX-8320
• Radeon R9 390X

I have the NoScript, Disconnect.me, and 1Password extensions.

NoScript was set to "Disable restrictions globally" for the console log provided.

Comment 4

[saikogekido]

Just updated to Nightly 85.0a1 tonight, and almost all of the unresponsiveness and input delay is gone.

Comment 5

[Andrei Purice]

Hey Saiko,
I tried reproducing this issue using the latest versions of Firefox Nightly 85.0a1 (2020-11-18), beta 84.0b5 and release 83.0 and could no identify any hangs, the whole process runs smoothly.
I've seen that "almost all of the unresponsiveness and input delay is gone" based on your last comment. Can we consider this issue resolved?
If it reoccurs you can try disabling some of the addons you're using 1 by 1 and see if that fixes the issue.

Comment 6

[JJ]

(In reply to Andrei Purice from comment #5)

Hey Saiko,
I tried reproducing this issue using the latest versions of Firefox Nightly 85.0a1 (2020-11-18), beta 84.0b5 and release 83.0 and could no identify any hangs, the whole process runs smoothly.
I've seen that "almost all of the unresponsiveness and input delay is gone" based on your last comment. Can we consider this issue resolved?
If it reoccurs you can try disabling some of the addons you're using 1 by 1 and see if that fixes the issue.

Hi Andrei,
I can confirm this bug also affects Linux users as well. I came across this bug report from https://forums.informaction.com/viewtopic.php?t=26058

The tl;dr of that thread:

• This issue only appears with NoScript enabled but...
• Newer versions of Firefox have improved the issue temporarily but has returned after a month or so (this was with Firefox 81.0.2). So perhaps there still exists an issue on the Firefox side of this bug.
• Issue does not appear in private windows, even with NoScript enabled.
• Thread title mislabelled as occurs with only one tab open.

Comment 7

[mymymanymany]

I also have similar issues with youtube.
I can confirm that disabling NoScript does remove the issue.
But:
The issue happens with no containers and in 1 container I use. Other containers I rarely use do not have this issue at all.
When the issue arises, it causes a big slowdown. Switching tabs takes seconds. Scrolling is slow. And the youtube page gets half loaded, as in some pictures get loaded others do not. And if most stuff is loaded, loading more videos also takes many seconds.
Opening a few youtube tabs also causes a slowdown.

I did some profiling:
https://share.firefox.dev/3gnYdlf

Comment 8

[Andrei Purice]

Setting a component for this issue in order to get the dev team involved.
If you feel it's an incorrect one please feel free to change it to a more appropriate one.

Comment 9

[JJ]

I think this bug has now been fixed with NoScript version 11.1.7 which firefox tells me it updated to automatically on the 22nd December.

The bug seems to have revolved around how NoScript dealt with serviceWorkers, not that that means anything to me, but apparently youtube now uses them, and so does twitter. NoScript has optimised its ServiceWorker related code in 11.1.7, and so voila, bug hopefully fixed!

Comment 10

[Henrik Skupin [:whimboo][⌚️UTC+1]]

Given that the reporter and JJ cannot reproduce the problem anymore now lets close the bug as WFM. Feel free to reopen the bug again in case you see the issue again.