I have not experienced this but 99% of my traffic to them is cloning repositories. Have you inspected your traffic in the web console of your browser? There is a network view that shows a waterfall of objects and how long it takes to get each one. I believe it also should DNS timing. It may be worth looking into that if you have time. If so I would start by clearing cache, closing the browser then opening and starting the web console in the network view so you get uncached data. Another step may be to disable all addons somewhere in your debugging as they can add red herrings.