[BUG] Zen (firefox fork) browser extension increased CPU usage

[PaulMcF1987]

Describe the bug
Firefox browser Extension Ramps up CPU usage.
With alias vault running, my CPU usage on Zen(firefox) is around 25%, when I disable this extension the CPU usage for Zen drops to around 1-2%

I disabled all extensions and re-enabled 1 by 1 to diagnose the problem extension and it turned out to be this one

with aliasvault enabled:

with alias Vault disabled:

[lanedirt]

Hi @PaulMcF1987,

Thanks for reporting this issue and for taking the time to narrow it down!

I haven’t been able to reproduce the high CPU usage on my end yet. Could you check if the CPU spike happens immediately after enabling the extension, or only when visiting/browsing a specific website or page? It would be especially useful to know if the behavior is triggered by certain website structures, as it might relate to the autofill mechanism.

[lanedirt]

Update: after installing the Zen browser on Mac myself (Firefox fork) I do notice the increase in CPU usage myself too. It seems to max out 1 CPU core instantly as soon as the extension is enabled. This however does not happen on the official Firefox browser for me.

I'll look into this further to see if I can pinpoint what is going wrong with the Zen browser specifically.

[PaulMcF1987]

It seems to run high for the full the that the extension is open

Untitled.video.-.Made.with.Clipchamp.mp4

You will see from the vido that CPU starts quite low (I have 2 browser windows open) when I enable Alias Vault it spikes and stays there until I disable it

[PaulMcF1987]

Update: after installing the Zen browser on Mac myself (Firefox fork) I do notice the increase in CPU usage myself too. It seems to max out 1 CPU core instantly as soon as the extension is enabled. This however does not happen on the official Firefox browser for me.

I'll look into this further to see if I can pinpoint what is going wrong with the Zen browser specifically.

I was actually going to ask if this might be specific to Zen. I also, wasnt sure if there might have been a conflict with bitwarden but it doesnt seem like that would be the issue

[lanedirt]

After some thorough debugging, I concluded the issue was caused by the AliasVault contentScript injectIcon method which injects the AliasVault autofill icon to login forms. If I remove this method call, the CPU drops. However the strange thing is, if I add an invalid if check around that method in content.ts, e.g:

            if ('aaa' === 'bbb') {
              injectIcon(target, container);
            }

Even though this change would prevent the method from actually firing, the CPU in the Zen browser still spikes to 100%. Also, the injectIcon method itself does not contain any issues that I can see, as it works properly in all other browsers.

After some digging in the Zen repository I do see that other people have reported issues with high CPU too:

• 2FAS Extension problem - abnormal CPU usage in 1.9b - no problems on Firefox (REOPENED) zen-browser/desktop#7057
• bug: High CPU usage on Zen Browser, regardless of website. twofas/2fas-browser-extension#117

The first issue mentions that this bug can be related to the New empty tab that the Zen browser opens. And I can confirm this, because if I kill the following process via task manager that causes the high CPU, the Zen empty tab crashes:

But after that tab has crashed, the CPU is back to 1-2% levels, and the browser still works:

It seems the Zen browser has applied a fix in this PR:

• fix: prevent attaching ID to empty tab in extension TabTracker zen-browser/desktop#7064

So I hope that in the next release of the Zen browser this issue will be automatically fixed. I'll keep this issue open so we can retest this issue in the Zen browser with the next release (> 1.10.3b).