I just bought 2 licenses of the Released Windows 8 and overall I like it except my browsers were hanging / locking up for about 20 seconds repeatedly. Apparently there is an issue with the dynamic tick. What it will do is stop Windows from coalescing CPU clock ticks when idle, a feature added in Windows 8 for power savings.
Run this to fix the problem. Worked for me:
Open Command prompt as Administrator
bcdedit /set disabledynamictick yes