The past several days the once speedy iPhone synchronization process had become glacial. By yesterday morning, a sync was taking 90 minutes.
I observed that the Microsoft Sync Manager was consuming large quantities of CPU frequently as well, and made a guess that Entourage calendar synchronization might be the root cause.
So, I rebuilt the Entourage database, deleted the Entourage calendar from iCal, relaunched Entourage and waited a few hours for it to reload all my email and calendar, re-enabled Entourage calendar synchronization, and now performance has returned to the previous speedy levels - just a minute or so.
Yet another justification for avoiding Microsoft products whenever possible. Unfortunately not possible in this case, as my employer uses Exchange, and refuses to enable IMAP email access — preventing me from using Mail.app. So the Mac users are forced to use Entourage. Yuck.
At least I can use OmniFocus for project management, Pages for word processing, Numbers for spreadsheets, and Keynote for presentations. All far, far superior to the Microsoft offerings.