Closed Bug 1776567 Opened 1 year ago Closed 11 months ago

Refreshing Youtube Subscriptions page freezes browser's UI


(Firefox :: Session Restore, defect)

Firefox 101



Performance Impact ?


(Reporter: tomek-kubel2, Unassigned)


User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:101.0) Gecko/20100101 Firefox/101.0

Steps to reproduce:

Refreshed Youtube Subscriptions ( page

Actual results:

After ~1sec, whole browser's UI froze for 8secs. This started happening recently ( 1-2 weeks ago). Link to recorded profile:

Component: Untriaged → Performance
Product: Firefox → Core

I can't manage to reproduce the issue on my end.
Is the issue only reproducible on that specific url?
Could you please try if the issue occurs in safe mode. Here is a link that can help you do that:

Flags: needinfo?(tomek-kubel2)

Just tested, issue also occurs in safe mode.

Flags: needinfo?(tomek-kubel2)

The time is spent in session store code, and a large percentage of it is spent in serializeCSP and serializePrincipal.

How many windows and tabs do you have open, roughly?

Performance Impact: --- → ?
Component: Performance → Session Restore
Ever confirmed: true
Product: Core → Firefox

1 window, 246 tabs

Thanks. We definitely shouldn't spend 4.4 seconds of CPU time to churn through 246 tabs, that's 17ms per tab!

The severity field is not set for this bug.
:dao, could you have a look please?

For more information, please visit auto_nag documentation.

Flags: needinfo?(dao+bmo)

I don't remember exact timeline, but some time after reporting this issue, the lag didn't happen immediately but after a delay of ~10s (so: refreshing > 10 seconds of nothing > 8 seconds of non-responsiveness). And few weeks ago, the issue stopped, no lag anymore. Should this ticket get closed now?

Thanks for the update. Closing

Closed: 11 months ago
Flags: needinfo?(dao+bmo)
Resolution: --- → WORKSFORME
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