Just leave it as default. If you really want to speed up vm, try moving the pagefile to another harddrive. Just think of it like RAM but many times slower. Lets say you only have 512MB in the system and if you open a program that needs around 1024MB. Then 512MB will be in RAM and the other 512MB will be in vm. Since the whole program will not be in ram it will greatly slow it down. Thats why many users suggest to upgrade the RAM first to increase system speed.