User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/15.0 Safari/605.1.15

Steps to reproduce:

Update to 91.
-Any any attempt to use a group mailing list results in almost immediate failure.
-CPU usage at 100%. Even when not doing anything in Thunderbird
-Searches in smart list fail to find all matches. Search for an email address and not all returned. I am unable to see why some are missing.

Actual results:

Type in the group name in the TO: field. Then just about any other action (type another name, subject line, or sometimes just wait a few seconds) Thunderbird fails and you can send in the failure report (did this many times)

Expected results:

Mail should be sent.
Note: I have downgraded to v78. (a pain since the old profile needs to be restored).

(In reply to Tyler from comment #0)

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/15.0 Safari/605.1.15

Steps to reproduce:

Update to 91.
-Any any attempt to use a group mailing list results in almost immediate failure.

Do you mean a group from macOS contacts?
What crashIDs do you have listed under help > troubleshooting?

-CPU usage at 100%. Even when not doing anything in Thunderbird

Do you have any language packs installed?

-Searches in smart list fail to find all matches. Search for an email address and not all returned. I am unable to see why some are missing.

Yes, from macOS contacts. Most frequent list has 4 entries. Note: Keying in each address works fine.

Crash ID:
bp-a205b042-ba60-4760-b08f-a60e20211012
bp-7db5d8fe-8843-4320-b603-e25550211011
bp-6f544ca7-dedc-46f6-ac6e-4faaf0211011

CPU throughout the day would frequently be 100%. Thunderbird was slower then v78. This morning it was 100% before I did anything. That is when I decided to go back to v78.

No language packs installed.

crash IDs start with (include) the "bp-" FYI

Your crashes are bug 1735508. AFAICT it only happens with groups, not contacts.

CPU usage reports that high are rare - I only find Bug 1729870 - high cpu usage idling on macos

bug 1735508 matches what I see. My group is also from Mac OS contacts.

Bug reports are best focused on one issue each. The crash is covered in 1735508. So if I may, let's focus this bug on the CPU issue.

https://mzl.la/3FR3ttK lists other recently reported performance issues. Unclear whether it contains a match.

I appreciate it's not much help, and I'd not even say it was a confirmation, but I have occasionally seen TB, on MacOS 10.15, stuck on 100% cpu, on Daily over the last few months, for no obvious reason. Nothing showing in Activity Monitor.

It's never been frequent enough for me to log a bug, especially with little to no useful data. It might be my imagination, but I don't recall seeing it as often over the last few weeks. Could be coincidence.

Is there anything I, or the submitter or others, can do to gather more data when this 100% cpu occurs, given nothing in Activity Monitor? Any logging that might be enabled either in TB or the OS (without restarting TB), whilst the condition is present?

It may be difficult or impossible to capture a performance profile https://support.mozilla.org/en-US/kb/profiling-thunderbird-performance, so my advice is to keep the error console and activity manager open, and consult them when you see high CPU.

No info from error console and activity manager ?

Tyler,
Does problem go away after Help > Troubleshoot mode?
Do you have non-default cursor size set in Mac?