Most people around here, myself included dont' advise "tune up" software because it's sort of like putting fuel cleaner in the gas for a busted radiator.
The better course of action is to have a mechanic look over the whole vehicle and tell you what's wrong.
Unfortunatly we can't crawl though the lines and tell you what's wrong with your machine, we can only advise based upon what you tell us and usually that's limited because your the one asking for help and if you knew already then you certainly would be asking questions.
So Iv'e laid out some information and links if you spend the time reading them help you understand your machine and thus can even provide us more information so we can assist you in asisting yourself.
This one here if you run the niffty little app, will tell us what's going on with your machine in more detail so we can advise accordingly. If you provide the data, we can provide better assistance.
Tune up your Mac here
This one here will tell you how the machine works and what issues can cause it to be slow
Why is my computer slow?
This one here will go about fixing your machine in a systematic manner yourself and explains just about everything.
Step by Step to fix your Mac
This one here will assist in Network related issues and slowdowns
Diagnosing network issues
This one covers your backing up of vital user data, which is mandatory before you do anything
Most commonly used backup methods