1833563 - zhihu.com loading very slow after scroll down several times

Status: UNCONFIRMED

(Core :: JavaScript Engine: JIT, defect, P3)

Description

[Tom25519]

​​### Basic information

Steps to Reproduce:

1. Open a page of zhihu.com, which have lots of replys and/or pictures, for example, https://www.zhihu.com/question/594727378 or https://www.zhihu.com/question/527323332
   zhihu.com loading very slow after scroll down several times, and high CPU usage.
2. Scroll down several times. The performance will be worse and worse.

Expected Results:
This bug should be prevent.

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Performance recording (profile)

Profile URL:
https://share.firefox.dev/3MwjtG3
https://share.firefox.dev/459g2gY

System configuration:

OS version: Windows 10 Enterprise LTSC 2021 x64
GPU model: HD4600, CPU i5-4690
Number of cores: 4
Amount of memory (RAM): 16 GB

More information

Please consider attaching the following information after filing this bug, if relevant:

• Screenshot / screen recording
• Anonymized about:memory dump, for issues with memory usage
• Troubleshooting information: Go to about:support, click "Copy text to clipboard", paste it to a file, save it, and attach the file here.

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Thanks so much for your help.

Comment 1

[Markus Stange [:mstange]]

The website is written in a very slow way, and also appears slow in Chrome.

However, there is something strange in the profiles you posted: The faster JITs aren't being used.

Do you have any non-default setting for javascript. preferences in about:config? For example, are javascript.options.ion and javascript.options.baselinejit set to true?

Comment 2

[Tom25519]

(In reply to Markus Stange [:mstange] from comment #1)

The website is written in a very slow way, and also appears slow in Chrome.

However, there is something strange in the profiles you posted: The faster JITs aren't being used.

Do you have any non-default setting for javascript. preferences in about:config? For example, are javascript.options.ion and javascript.options.baselinejit set to true?

No. All javascript. preferences in about:config are keeping default.

Comment 3

[Alex Thayer [:alexical] (she/her)]

Iain, do you have any ideas what else might be preventing this from tiering up and any further information we may need to ask for from the reporter?

Comment 4

[Iain Ireland [:iain]]

Testing it myself, I see plenty of time spent in Ion, so it's not a universal problem.

Is the performance any better with a fresh user profile?

Comment 5

[Tom25519]

(In reply to Iain Ireland [:iain] from comment #4)

Testing it myself, I see plenty of time spent in Ion, so it's not a universal problem.

Is the performance any better with a fresh user profile?

Now I using Firefox 114.0.1, the performance seems better than before (even before refresh firefox), but it seems that firefox doesn't use all of CPU (i.e. 25-40% overall), is this a normal phenomenon?

Comment 6

[Iain Ireland [:iain]]

(In reply to Tom25519 from comment #5)

Now I using Firefox 114.0.1, the performance seems better than before (even before refresh firefox), but it seems that firefox doesn't use all of CPU (i.e. 25-40% overall), is this a normal phenomenon?

In general, if there's work to do, I would expect us to be using 100% of one core to run the main thread (unless we're stuck waiting for the network), and sometimes making use of background threads for compilation and other tasks. If you have a four-core machine and your OS is reporting CPU usage as a fraction of the maximum possible usage, that might show up as 25-40%.

If you put up a profile, I can take a look.

Comment 7

[Tom25519]

https://share.firefox.dev/443AwX3
https://share.firefox.dev/43FCFIv

Comment 8

[Tom25519]

Will set javascript.options.mem.gc_parallel_marking = true improve the performance? After some time my last update on this bug, I tune this option manually.