Affected versions

• 102.0a1 (20220504234551)

Affected platforms

• Windows 10x64
• macOS 12

Steps to reproduce

1. Open gmail.com and log in.
2. Create multiple tabs of Gmail (10 or more tabs)
3. Set Firefox to open Previous Windows and tabs and close Firefox.
4. Open Firefox and click on Gmail tabs to load them.

Expected result

• The Gmail pages are loaded.

Actual result

• Firefox freezes.

Regression range

• Last good revision: 9bfc934172e97f7f7a7f80bc0cfe569f4b2964a1
  First bad revision: 63f17a06eba94aceaeffd3ecb526f4cdbb7f4067
  Pushlog:
  https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=9bfc934172e97f7f7a7f80bc0cfe569f4b2964a1&tochange=63f17a06eba94aceaeffd3ecb526f4cdbb7f4067

Notes

• Screen recording attached.
• The issue can be reproduced even by opening multiple tabs of Gmail by using the Duplicate tab or entering the URL on a new tab without session restore.
• I have also encountered some crashes while testing this, but I don’t know if these are related tho:
  https://crash-stats.mozilla.org/report/index/58e39302-e03a-4960-94f4-702b20220505#tab-details
  https://crash-stats.mozilla.org/report/index/a5294e61-173a-4321-8f95-1aa3f0220505
  https://crash-stats.mozilla.org/report/index/2db4f82d-5890-42cc-b4a8-9eb590220505#tab-details
• The regression range may be inaccurate there before maybe the component is not the right one. Please feel free to change it if so.
• S2 because this can happen at startup when loading a Gmail tab or having Gmail Pinned tabs as well.

I can reproduce this on startup with 2 pinned Gmail tabs.

Set release status flags based on info from the regressing bug 1754004

:nika, since you are the author of the regressor, bug 1754004, could you take a look?
For more information, please visit auto_nag documentation.

Fixed by backout of bug 1754004.

The issue is no longer reproducible with Firefox 102.0b3 (20220602190016) on Windows 10x64, macOS 11, and Ubuntu 20 by following the STR from comment 0 and by having multiple Gmail pages pinned while opening Firefox.