This phenoemenon makes Outlook 2011 essentially useless for me. I have observed it for over a year now, running "Maverick" and all most recent updates/upgrades. None of the recommended actions helps - neither re-installing the software, nor switching from my 2013 Retina MBP to an older Mac Pro, nor emptying cahes, nor rebulding the database. It happens primarily when connected to an Exchange server at work or remotely, whether via VPN or not. Every few minutes, the beach ball spins and Outlook 2011 hangs. Can't even minimize the window. Watching what happens shows that it's when any folder - inbox, deleted items, calendar, whatever - is synchronized with the server.
Many of my colleagues expoerience the same. Neither Microsoft nor Apple have remedied these problems since 2011. At this point I can only conclude that this either reflects incredible incompetence of the MS software team for Mac, or deliberate sabotage of the Apple platform. After 20 years of using many different email clients without any problem ever, Outlook 2011 is obviously incapable of performing the simplest and most trivial email client tasks - synchronizing with an Exchange server without stalling. Most likely the reason is simply that instead of synchronizing in the background, this dumb software synchronizes in the foreground.
All Microsoft has to offer to help is a schoolmasterly borderline arrogant support page post that proposes actions which may reduce somewhat, but in my experience will definitlely NOT repair the flaw. The guy who wrote it should be fired and competent developers hired. But I suspect MS has no interest in that. That, likely, is also why Outlook 2011 still is not iCloud compatible and in contrast to good old Exchange for Mac can not synchronize contacts and calendar items with the Apple address book and calendar.
It is time for strict regulation of the IT industry, and for rigorous consumer protection laws.