1676748 - High CPU usage even with new profile (Windows 10)

Status: RESOLVED INVALID

(Thunderbird :: Untriaged, defect)

Description

[cdf]

Attachment: 2020-11-12 Thunderbird 78.4.3 CPU usage.png

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:82.0) Gecko/20100101 Firefox/82.0

Steps to reproduce:

Yesterday I updated TB from about version 54, to 68 then 78. Both 68 and 78 showed excessive CPU use (~20-30%) when idle. (I'd had no problem previously.) I usually have 2 instances of TB open with different profiles, so I now have 50-60% CPU being used by TB.

Actual results:

Attempts to solve:

1. I upgraded to 64-bit from 32-bit -- no difference. (Currently on 78.4.3 64 bit)
2. I created a new profile and haven't added any email accounts or anything. The CPU usage for the new profile is usually about 17-20%
3. I increased mail.db.idle_limit as per issue 1305207, but no difference.
   Here is a profile report from the empty profile: https://share.firefox.dev/3loJicf

Expected results:

Near 0% CPU usage when TB is open, but I'm not doing anything in it.
BTW, I have Check for messages turned off; also Global Search and Indexer off.

Comment 1

[Wayne Mery (:wsmwk)]

Please check tools > activity manager for activity.

Comment 2

[cdf]

With the empty profile there is nothing showing in Activity Manager
In my normal profile there are occassional entries for checking email (done manually every few hours), and moving/deleting emails; nothing else.

Comment 3

[Magnus Melin [:mkmelin]]

Also check if disabling hardware acceleration in the thunderbird preferences makes a difference.

Comment 4

[cdf]

Wow, I'm not sure what happened, but when I checked this morning TB is showing near 0% CPU in both the empty and normal profiles! Coincidentally, or not, Firefox is the same: its CPU use has been really high for months (even with only a couple of tabs open), but today it is really low, too (hovering at 2% or below, even 0% at times, which is unbelievable!)

The only change in my system (that I'm aware of) is that Windows did an update over the weekend: https://support.microsoft.com/en-gb/help/4586781/windows-10-update-kb4586781.

Looks like this issue can be closed. Thanks for the support!

Comment 5

[cdf]

I thought it seemed too good to be true! Now, a few hours later, the CPU usage has gone back up in both TB and FF! So it must be an interaction with some other application or process that has been started in the meantime. I've stopped my backup service and other background app that I started. Also tried turning off Windows' "Real-time protection" (which was on when I was seeing ~0% usage), but no change. I guess this is now a case of "not TB's fault", however, it is curious that both TB & FF show the same effect. Any tips/thoughts on what it could be? I will keep trying to track it down.

Comment 6

[Wayne Mery (:wsmwk)]

Thanks for the update.

AV software has been known to cause higher CPU in applications. Something in https://www.google.com/search?client=firefox-b-1-d&q=antimalware+service+executable may help.

Comment 7

[cdf]

I've been doing some testing with Windows Safe mode and TB has sometimes dropped from 20+% down to 0% after 5-10 minutes in Safe Mode No Networking; but I can't seem to be able to record a profile without internet. In Safe Mode with Networking it is the normal 20+%, even though I'm not connected to the network since wifi is disabled in that mode.

Just now I was surprised to see TB at ~0% in my normal profile, normal Windows. It then ramped up to 20+% for a couple of minutes, then settled again. It has now been at ~0% for over half an hour, but I was able to take a profile in both states:

Profile 0% CPU [https://share.firefox.dev/37CEhZf]
Profile 20% CPU [https://share.firefox.dev/3awyyGd]

The 20% one shows a lot of rendering/painting activity, which it shouldn't be doing when TB is idle -- I'm not doing anything, it is just sitting in the background open at the Local Folders Inbox, with the calendar closed.

Comment 8

[Wayne Mery (:wsmwk)]

Please post a screen shot of thunderbird during this higher CPU

Comment 9

[cdf]

Attachment: 2020-12-20 TB Normal - Normal [23%][Screenshot].png

Screenshot attached showing TB & Task Manager. Note that Firefox is also open with one tab (the profiler) and also high CPU. Yesterday when TB was ~0%, FF was also <1% so there really does seem to be a connection.