Outlook for Mac 2011 has always been a real laggard - slow and unresponsive - so I was glad to hear M$ released a new version (Outlook for Mac Office 365) that was supposedly a lot better. So I installed it. And then I uninstalled it. Why? Because it was a CPU hog. I wondered why my fans were always revving up to high, so I started launching Activity Monitor. It would report Outlook consuming almost half of my quad-core i7's computing power! So I dumped it and went back to Office 2011, crappy as it is. Oh, by the way, I go through this torture only because at work I have to use Outlook. For all my personal stuff I leave M$ junk software alone and use better alternatives. It's just amazing how bad their software is. You've been warned!