IMAP GMAIL DOWNLOADING THOUSAND OF MAILS CONSTANTLY
On my laptop, I have one gmail IMAP account set up. It is quite old and has tens of thousands of messages stored in many folders.
Mail.app is caching them locally, but frequently it seems to feel the need to re-download many thousands of them. The Mail Activity panel always shows things like "Incoming messages: 4507 of 10833, 53 KB/s".
If I look at the activity window, it is synchronizing IMAP folders ... and the folders it is synchronizing haven't changed in over two years: I have stopped storing new messages in them. So it should already be synced, and Mail.app shouldn't have to download new messages anymore. But it re-downloads them often.
I don't think the problem is with the folders on the server, It is a gmail account, which I'd assume Google configures intelligently. Though, the desktop is on all the time and Mail is always open, so maybe it does re-download them frequently but I don't notice.
It's very annoying because it pegs my processor at 100% for about 20 minutes every time it happens, which is often. Slows down the machine and heats it up enough to burn my lap in just a few minutes!
Any thoughts on how to get Mail.app to be sane about syncing local copies of remote IMAP messages? This is ridiculous.
MacBook Pro with Retina display, OS X Mountain Lion (10.8.3)