What happens if you try it in Windows safe mode (Shift+Restart)?

Did you ever read the describing of my problem? I've mentioned about safe mode.

I took your comments to mean TB safe mode, which tests for incompatible add-ons etc, whereas Windows safe mode tests for incompatible security programs etc., a common cause of slow attachment handling.

https://wiki.mozilla.org/Thunderbird:Testing:Memory_Usage_Problems

As additional info, tb is on ssd, clean windows, no firewall, no av. Safemode check is dead way in this situation. Problem prtsist on many pcs with 100% same sympthoms.

egor_sh said

As additional info, tb is on ssd, clean windows, no firewall, no av. Safemode check is dead way in this situation. Problem prtsist on many pcs with 100% same sympthoms.

We all know windows 10 is at best beta quality, especially if it has been upgraded. So I would not say any diagnostic test is ""dead way"

But perhaps your asking a lot. Outlook converts all attachments to a file on arrival, it is part of the standard PST database. Thunderbird performs that action at the time you ask for the file to be opened, so a conversion from mime to whatever format is required is done and the file written to disk in the temp folder. after you select to open the file.

BTW, I would be very nervous with many unsecured PC's around. I would expect ransom ware to be a frequent problem.

I'm using win 8, win 7 sp1, win 2008r2 with all updates for testing. Seems like such freezes is by design. Sad to know that.

egor_sh said

I'm using win 8, win 7 sp1, win 2008r2 with all updates for testing. Seems like such freezes is by design. Sad to know that.

I have no idea if it is "by design". Really I think you should file a bug, even if it is "by design" https://bugzilla.mozilla.org/

There is a fix for attachment speeds in 56.0b2. Does it solve your problem? see https://www.mozilla.org/en-US/thunderbird/channel/

Seems like beta version is much faster!