Follow the steps given below
1) Hold down the 'Windows' Key and Press the 'Pause/Break' button at the top right of your keyboard.
Another way is Right-Clicking 'My Computer' and then Select 'Properties'.
2) Click on the 'Advanced' tab.
3) Under 'Performance', click 'Settings'.
4) Then click the 'Advanced' tab on the button that pops up.
5) Under 'Virtual Memory' at the bottom, click 'Change'.
6) Click the 'Custom Size' button.
7) For the initial size (depending on your HD space), type in anywhere from 1000-1500 (although I use 4000), and for the Maximum size type in anywhere from 2000-2500 (although I use 6000).
8) Click 'Set', and then exit out of all of the windows.
9) Finally, Restart your computer.
10) You now have a faster computer and 1-2GB of Virtual RAM..!