Interesting problem today - while running Zimbra on my spiffy new laptop and Vista Zimbra was veeerrrryyyy slow to load up (10 sec pauses between every css or js file download). After investigation discovered that turning off the McAfee Phishing filter (as came with the Dell laptop) solved the problem. Problem occurred on IE7 and FF 2

Note that our DNS is a bit funky so this may have also contributed.