[avar]

Yes, I use the SQLite driver, and use & regularly pull the latest version from the git, 7.1 right now.

I haven't dug into why it uses that CPU in any detail. Looking at its output / tcpdump of what it's doing it goes to >100% CPU for 10-30 seconds when it's finished fetching the status from the remote & is presumably in some tight inner loop comparing it with local data to decide what to do before it starts downloading messages, and then briefly spends a few more seconds at >100% after the messages are downloaded, presumably updating its local state.

When it's just issuing IMAP commands or downloading messages from the remote it sits at 1-5% CPU.

As I pointed out OfflineIMAP works just fine for me, but in retrospect I'd be happier if I had stayed with mbsync. I don't need any feature from OfflineIMAP that it doesn't have, and it both uses less CPU/Memory & it finishes deciding what to download & downloading it in way less time.

[TobyGiacometti]

I have just checked how much it uses on my side: doesn't go above 50%, but I do consider that pretty high and can totally understand how it could use 100% with bigger mailboxes. For me, this was never a problem since I only run it once daily for backup.

Thank you for mentioning mbsync, I will keep it in mind.