Connections to some sites time out from OS X but not from Windows, how to diagnose? For the past couple of weeks I have noticed some sites take longer to finish loading. GMail would be one example; after the site is loaded and fully usable, the spinning indicator in Chrome’s tabs will remain for a couple of minutes. Safari behaves the same. Right now reddit doesn’t load at all. Pinging www.reddit.com results in 100% packet loss. Their address resolves to an Akamai IP, so if everything delivered via Akamai is timing out, that would explain why quite a lot of sites are affected.

Loading those same sites from my boot camp partition works like a charm, same goes for my iPod, so the router as well as the ISP can be ruled out as the reason for this. What can iIdo now to diagnose the problem?
"Do pages often "stall" and then time out halfway through loading? (And then you hit the "stop" button, and refresh, and magically, they appear?) I just had this happen, and fixed it by manually turning "off" IPV6 (from the default setting of "Automatic") in the Advanced area of the Network settings control panel. "

I found this tip to work in conjunction with setting my DNS to google or freeDNS.