Thunderbird Doesn't Play Well With Windows 10?

I have long noticed that when you opened more than five tabs in Opera under Windows 7, it hogged RAM so badly that it often just whined and shut down.  Under Windows 10, no better, but even after you close Opera, Windows crawls.  The mouse is so jaggy as to be unusable.  Restart fixes it.  If I use Chrome, Thunderbird, and Outlook (my most common applications), everything works fine.

As much as I believe in "Google delenda est," Chrome is required by College of Western Idaho's cranky website (at least Blackboard), so I am stuck with it.

Not Opera, perhaps, but Thunderbird.  There is a fix.  And it apparently slows down battery drain and reduces CPU temperature.  Thunderbird has been running long enough now to report this fixed the bad case of the slows.  No, still eventually brings it to a crawl.  A bit more experimentation is required to find the guilty party.  Task Manager in Windows 7 would show just applications so you could identify the guilty party.  No longer.  You see all processes including Windows internal processes.

That fix for Thunderbird:  I appear not to have hit OK after changing that property.  Trying again to see if this works.  It also might be that there was corruption in the msf files, so I deleted them and restarted Thunderbird.  So far, looking good.  And the longer idle period seems to have made it worse.  Shorter interval?  If there is a fixed amount of work to do at idle, that will not help.  But who knows what that idle interval does?  Try that next.  That seems to have worked.