accountsd process using exhorbitant amount of CPU

Mail typically does not use a lot of CPU for more than a few seconds... and not nearly as much as shown in the screen grab I included. For instance, here is a screen grab I just took now....

It seems (not scientifically confirmed) that both accountsd and Mail spike in CPU usage at the same time... perhaps when Mail is checking for new messages...? At that time, accountsd CPU usage is between 100 - 220% roughly while Mail CPU usage is around 40 - 85%.

Have I been having trouble with Mail...? Well, let's see, only for the past 2 years... across 3 OS releases. On a fairly predictable cycle (about once a month) Mail dies suddenly. Then it won't start up again. I get the crash report dialog. I have to go manually delete files according to the instructions here:

https://appletoolbox.com/mail-not-working-in-macos-catalina-how-to-fix/

I also a new post in these discussion forums.... can't find it now 'cause your site is all bollixed up and says I have no posts. Nice....

So, am I having problems with Mail...? Yes indeed. Are they related to this high CPU usage? I don't know.

Not seeing anything related to iCloud or keychain. Nothing else looks suspicious.

The high CPU usage happens regularly... every few minutes. It quiets down. But it seems that each time I notice accountsd using a lot ofCPU, some other process is consuming between 40 - 65% CPU. For instance ,right now as I'm typing this, I'm downloading Xcode new version from the App Store. The install process is devouring 60% CPU. Disk usage is minimal.

Didn't try yet. Had to backup my system via Time Machine.

Is there a way to reinstall Catalina by re-downloading the entire OS? I don't trust ANYTHING at this point. I back up my system daily, but this problem has been ongoing for a long time... Mail, even Activity Monitor (in Disk view display does not update), Photos 5.0 won't export photos... and a whole bunch of other apps exhibit peculiar behavior.

What exactly am I looking for in Safe Mode?

If my observed problems don't appear in Safe Mode it doesn't eliminate 3rd party software versus Apple software. And if the symptoms still appear, it doesn't tell me what parts of the system cause those symptoms.

And, as far as I've been able to tell so far, it's Apple software that's the problem.... Mail, Photos, Activity Monitor, Time Machine, etc. CPU usage is through the roof only when Apple software is running.

What information should I capture in Safe mode?

Update....

Reinstalled Catalina 10.15.4 from network....

Things are running better but still suspiciously. I cannot say if the system is running normatively because, admittedly, I'm scrutinizing it more closely.

I still find it strange that Mail CPU usage jumps to 20 - 30% just as a result of me bring the screen focus to the Mail window.

Incidentally, I found this post where people are having trouble with Mail causing high CPU usages on 10.15.4 Catalina:

https://www.reddit.com/r/MacOS/comments/g1qssa/apple_mail_causing_significant_power_usage_and/

By the way, running in Safe Mode was astronomically worse...

WindowServer ... 100%+ CPU... 20%+ when NOTHING happening, not moving mouse, not Cmd-TAB'ing, nothing...

CVMCompiler using 100% CPU

MTLCompilerServer using 100% CPU

Naturally, this CPU percentage reporting is still brain dead... a remnant of the flawed BSD Unix algorithm. Guys, just go get the Open Solaris code and port it and give users something that makes sense...

I did not uninstall any 3rd party software. The only 3rd party software I have is:

MalwareBytes

TurboTax 2019

LibreOffice

Chrome

Adobe Acrobat Reader DC

GIMP 2.0

The high CPU usage problem existed months and months before TurboTax or Adobe Acrobat Reader DC or GIMP were installed. The others, Chrome, LibreOffice are not running unless I'm using it actively. MalwareBytes is running in the background, but I never saw high CPU usage from it.