1559677 - Intermittent Lag composing new email. Low/no CPU. But MsMpEng.exe (Windows Defender) uses a full core CPU.

Status: REOPENED

(Thunderbird :: Message Compose Window, defect)

Description

[laurens]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:67.0) Gecko/20100101 Firefox/67.0

Steps to reproduce:

Using Thunderbird against gmail account.

No extensions
No plugins
Check spelling is enabled, but there are no dictionaries
Core i5 computer
Windows 10

Actual results:

Sometimes typing a new email becomes extremely laggy - 200ms when typing words, moving the cursor, etc
Have to close and reopen Mozilla thunderbird
There is no abnormal CPU usage

Expected results:

Able to compose email without lag.

Comment 1

[Benjamin Flanagin]

Laurens,

Thanks for all the info, did you happen to notice any memory usage spikes? Even if the CPU isn't being utilized much sometimes a memory leak can cause similar results.

Comment 2

[Magnus Melin [:mkmelin]]

FWIW, I used to see this some, but it got much, much better from tb 60 -> 68. I don't really see it ever now.

Comment 3

[Wayne Mery (:wsmwk)]

If you see this in safe mode in verison 68 please repopen the bug.

Comment 4

[laurens]

68b3 - still get periodic lag (now a couple of words behind) with the Gmail (IMAP) accounts but fewer occurances.

Almost as if checking / sync of mailbox is in the same thread as the composing?

68 does appear to be better than 67 - which changes were made that were expected to have an effect?

Comment 5

[laurens]

Hi - trying to reopen as Thunderbird is basically unusable to me as a productivity tool (e.g. gmail's otherwise annoying web interface is actually faster to type on)

TB Ver 69.0b3 (32-bit)
Win10 Pro
Core i5
SSD

Gmail accounts via IMAP, both about 9k messages.
Trying to compose a message is laggy - like on a 300baud modem.
Tried in Safe mode - no difference.

I notice that MsMpEng.exe spikes to a full core when I try to type in Thunderbird - I think that there is some incompatibility between TB and MS security.

Comment 6

[Benjamin Flanagin]

I can confirm a less dramatic lag here during certain events: Checking mail, running filters, etc. Nothing as extreme as what comment 5 describes. However, adding Windows Security and using a 32bit version might be enough to cause a minor issue to turn into a huge one.

Laurens,

For testing purposes can you disable MS Security for a few minutes while you're composing a message? Given that you are pulling the mail from GMAIL and the fact that GMAIL scans for viruses on their end the threat is some what low. If the composition window is less laggy then it narrows down the amount of possible issues.

Comment 7

[laurens]

(In reply to Benjamin Flanagin from comment #6)

I can confirm a less dramatic lag here during certain events: Checking mail, running filters, etc. Nothing as extreme as what comment 5 describes. However, adding Windows Security and using a 32bit version might be enough to cause a minor issue to turn into a huge one.

Laurens,

For testing purposes can you disable MS Security for a few minutes while you're composing a message? Given that you are pulling the mail from GMAIL and the fact that GMAIL scans for viruses on their end the threat is some what low. If the composition window is less laggy then it narrows down the amount of possible issues.

Sorry - work got in the way. In fact later on that night I added
Win10 x64
Microsoft Security (built-in)
Add Folder to Exclude list
C:\Users$Username$\AppData\Roaming\Thunderbird

Restart TB

This seems to stop all the lag from the brief testing that I did, also MsMpeng no longer uses an appreciable amount of CPU whilst typing in TB.

So that works as a workaround...

Comment 8

[Wayne Mery (:wsmwk)]

Thanks for listing the workaround. Unfortunately, we do not have significant control over the impact of Windows Defender. FWIW we have many reports of AV issues https://mzl.la/34Oad9A

But we'd be interested in your findings if something like disabling spellcheck or saving drafts helps when the defender exclusion is removed.

Comment 9

[laurens]

(In reply to Wayne Mery (:wsmwk) from comment #8)

Thanks for listing the workaround. Unfortunately, we do not have significant control over the impact of Windows Defender. FWIW we have many reports of AV issues https://mzl.la/34Oad9A

But we'd be interested in your findings if something like disabling spellcheck or saving drafts helps when the defender exclusion is removed.

I respectfully ask this to be returned to a bug status. Win10 is a major TB platform. MSE is the default anti-virus. The fact that the default appears to give a terrible UX for TB users should be a major issue, else people will stop using TB. Getting them to disable virus scanning is not an option for most (corporate environments) or because it's a PITA to do, never mind the security implications...

"unfortunately, we do not have significant control over the impact of Windows Defender. FWIW we have many reports of AV issues"
I use dozens of engineering programs on windows, and none of them appear to be impacted, therefore there must be something fundamental in the way that TB is architectured that causes this.

Comment 10

[Wayne Mery (:wsmwk)]

I understand you are in a tough spot. But there are certainly plenty of Thunderbird users with Defender who don't see problems If defender uses a full core - how do you image we are to fix that? They messed up.

Example of an AV that plays well, and defender does not https://bugzilla.mozilla.org/show_bug.cgi?id=1332487#c4
More examples
https://bugzilla.mozilla.org/show_bug.cgi?id=1208116#c9
https://bugzilla.mozilla.org/show_bug.cgi?id=1128283#c9

Comment 11

[laurens]

Wayne, you seem adamant that this is not a fundamental issue with TB, nor that there are any security implications with disabling scanning of those folders.
I am not convinced of either of those without more than anecdotal evidence.
I can imagine that, for example, repeated writing to a database object in the Appdata folder could be triggering constant scanning by MS Defender, in which case it could be a TB architecture issue that is solvable....

Comment 12

[Wayne Mery (:wsmwk)]

I understand your position. But yes, I am fairly confident especially given that other antivirus products don't cause a problem.

Multiple contributors with decades of experience with the Windows PC environment in https://wiki.mozilla.org/Thunderbird:Testing:Antivirus_Related_Performance_Issues#My_Problem_Cannot_be_Caused_by_Antivirus attest to AV issues. Not mentioned there is AV features are unnecessary and problematic. Also, a Thunderbird option which might help is "Allow antivirus clients to quarantine individual incoming messages"

Comment 13

[Frank-Rainer Grahl (:frg)]

Try turning off Cloud based protection and automatic sample submission. In the Windows 7 version this is under MAPS and Advanced.