I run Thunderbird on my Windows 10 host, with MS Windows Defender AV. I notice that Thunderbird slogs down my PC when it is compacting. The Mozilla "Compacting Folders" help site suggests possibly changing the threshold and checking if Antivirus is getting in the way. I have not checked whether Windows Defender is interfering yet, but I had an idea to disable automatic compacting if there was a way to start a compact via command line, which I could start via a Scheduled Task at times when I'm not working on the PC. (I let the PC run on Sunday to do a RAID verify and run backups. It would be a good time to compact, too.)

Is there a way to make Thunderbird start a compact via command line?