How to diagnose performance problems in Windows Vista?

Start from Performance Information and Tools in Control Panel.

It can check problems of many programs in the Performance Information and Tools screen, and then revising them automatically.
Performance diagnosis provides two ways to check and maintain Windows Vista general problems, such as media cannot play normally, applications start slowly, operating system starts slowly, and the network connects slowly etc.
After confirming performance problems, user can follow the steps to solve the problems.

 
[Windows Vista]How to evaluate the PC’s performance. 

For making use of Windows Vista to diagnose performance status, please refer to the following steps.
1.Click the Start button, and then click Control Panel.

2.After displaying Control Panel, click System and Maintenance.

3.Click Performance Information and Tools.

4.Displaying Performance Information and Tools screen.
Click the items appear in Rate and improve your computer’s performance.
5.Different details will show up according to different items.
*Click Help button to show how to avoid the problems.