As with all past versions of Windows if your PC is running slowly, you can speed it up by disabling some of its visual effects. It comes down to appearance versus performance. Would you rather have Windows run faster or look prettier? If your PC is fast enough, you don't have to make this tradeoff, but if your computer is just barely powerful enough for Windows 7, it can be useful to scale back on the visual bells and whistles.
You can choose which visual effects to turn off, one by one, or you can let Windows choose for you. There are many visual effects you can control, such as the transparent glass look, the way menus open or close, and whether shadows are displayed.
To adjust all visual effects for best performance:
1. Open Performance Information and Tools by clicking the Start button, and then clicking Control Panel. In the search box, type Performance Information and Tools, and then, in the list of results, click Performance Information and Tools.
2. Click Adjust visual effects. If you're prompted for an administrator password or confirmation, type the password or provide confirmation.
3. Click the Visual Effects tab, click Adjust for best performance, and then click OK. (For a less drastic option, select Let Windows choose what’s best for my computer.)