Why your computer slows down over time is most often due to two reasons: too many entries added to the Windows registry that you do not use, paired with a decrease of space on the Windows drive or auto running to many programs that you do not need either way.

Learn the Windows 7 shortcuts using your keyboard:

You can make life much easier for yourself if you learn the various keyboard shortcuts on Windows 7.

Windows key + Home = minimize or restore all windows/programs other than your active window.

Windows key + Up arrow = maximize a window.

Windows key + Down arrow = minimize or restore a window.

Windows key + M = minimize all windows.

Windows key + Left arrow = dock window to the left hand side of the screen.

Windows key + Right arrow = dock window to the right hand side of the screen.

Alt + Up arrow = used in Windows Explorer to go to the parent folder.

Alt + Left or Right arrow = used in Windows Explorer to go Back or Forward through folders.

Alt + Windows key + corresponding number of program on the taskbar = shortcut to access a specific program's Jump List that sits on the taskbar.

Windows + Shift + Up Pressing these three keys while a window is active will stretch it vertically to the maximum desktop height. The width will remain the same. Pressing Windows + Down will restore it to its previous size.

Windows + Space This shortcut makes every active window transparent so you can view your desktop. The windows only remain transparent as long as you're holding down the Windows key.

Windows Key + Shift Key + Left or Right Key Shift the window from one monitor to another. If you are using two or more monitors, then you might want to move the Windows from one to another. By pressing Windows Key + Shift Key + Left or Right Key.

The right(click) stuff. In Windows 7, right clicking can simplify your computing experience in many ways.

Switch hitter. Switch through multiple documents in a program with ease -- simply press CTRL while you repeatedly click the program icon on the taskbar.