A system restore to factory settings can solve issues with a multitude of things, but for it to work the trick is knowing as to how to go about the whole procedure correctly.
For computers if system restore has been unable to solve the problems, then a factory restore is a possibility that should be considered carefully. But it needs to be thought out first.
If your computer is running too slow, it may be for other reasons. This method whilst not being over difficult is not for the beginner.
Whilst not being too complex in the actual operation it is the copying of files and their re installation which is both time consuming and perplexing.
You could spend several hours going about this to find that your computer or laptop once reset to default is running just as slow or has inherited some system problems which are causing issues.
However a smooth and straightforward restore and your computer should be as good as new.
I carry out this process at least every few months, as over time all computers run slower because of the file transfers and movement of data that is involved in the computing process.
Restore to factory will erase all data and programs installed since you purchased the computer and return it to the state that you bought it in, as it left the shop. Any programs that you have installed yourself will be lost and these cannot be copied from your computer.
You need to ensure that you either have the cd or media you did the program installation from or you that can download a fresh installation from the web.
Also ensure that you know your passwords.