Guild Wars 2

In Windows 8, there is a new energy-efficient method for handling processor load. On-paper, your computer should perform well under general usage, and use less energy while idle.

This new method however can cause issues on some hardware, and may not even be wanted at all on Desktops focused on pure performance. In the past, this was more problematic for users, but a Windows Update has solved the problem of system lock-ups. Regardless, you may still be interested in disabling this option.

You will want to run this from an Administrative Command Prompt and reboot: bcdedit /set disabledynamictick yes

And after the reboot, you should check to see if you notice any improved performance.

Notes:
- Advice taken from: http://www.withinwindows.com/2012/06/28/workaround-for-windows-8-freezing-issues/
- This is only for Windows 8 (and Server 2012)
- This will increase power usage on idle, may be a concern for mobile users
- You should either have increased performance on general tasks, or no change at all if it was working properly (but you should not have worse performance)

the change that helps on 7 and lower(may work on 8 as well) is to force HPET (or in the case of first gen i7/i5, you want to diable it in bios and still use the commend to force best timer)
http://forums.guru3d.com/showpost.php?p=4412171&postcount=11
http://forums.guru3d.com/showpost.php?p=4412312&postcount=17

i have tested this on older amd to the latest amd no problems at all, the only platform i have seen issues from it on are first gen i series intels, and if you disable it in bios you still get a better timer then the mix of timers windows vista/7/8 use by default(forces windows to use the newest/best timer)

give it a go, even works on some of those old i5/i7 systems, but its very hit and miss(no harm trying it!!!)