The real performance hit in Windows Vista is within its power management settings. In the advanced settings, there are spots to set the minimum and maximum CPU speed. Even on "high performance" the minimum isn't set to 100%, so to fix the problem, either create a custom profile or just edit the "high performance" profile to have a minimum and maximum CPU speed of 100%. This will cause Vista not to slow the CPU down, so you will have ultimate performance. Vista runs better and there is a noticeable responsiveness to it when the CPU setting is fixed. This setting is good for desktops and laptops on plugged in power. Adjust as needed for laptops on batteries, but that should be on a separate power profile, anyway.
                                                                                                    By Muhammad Irfan