they all do that, I can't tell you why but if you google it you'll see how many hundreds of people report the same problem. There are a few little "tricks" out there you can do that help, but none will fix it completely. Not really a lot of choice but to wait for an update from microsoft to fix the lag, should be comming since there are a LOT of complaints about this. Best remedy for now is using a USB device, either a flash drive or an external hard drive depending on how much media you have, and plug it into the usb port on your 360 and browse it that way.
