Installing more RAM into your computer which will allows it to run faster.
To put it another way, your RAM generally does not make your PC faster, it just allows it to do more things at once. If your single application uses 200 MB of RAM, it won't matter if you've got 2 or 8GB of total system memory, but if you've got 10 windows open using 200 MB each, then you are probably going to benefit from an upgrade.
