I did the compact (I was wondering where they hid it in Outlook 2010) but I don't think that is the answer. Just now it took one minute to send a 2KB e-mail. My ISP is wireless. A speed test said ping at 28 ms, upload 0.4 Mbps, download 2.8 Mbps. What bugs me is that sometimes an e-mail goes in a second, sometimes takes several minutes, and sometimes not until I reboot.
The ScanPST found and fixed 24 errors but a 2 KB e-mail got stuck in the outbox. After restart of Outlook stuck "sending 5 of 5". One more restart and the one e-mail in the outbox was sent in a flash.