Welcome to TSF.
How many anti-malware programs do you have running?
One or two should be enough - have a look at this guide:
PC Safety and Security--What Do I Need?
Remove all startup programs - except your anti-malware and firewall.
To do that:
Click Start > Programs > Startup. Drag the "unwanted" programs out of that folder and drop them another place in the Programs menu.
Download and run
CleanUp.
Please read the "warnings" first.
Download and run
Auslogics Disk Defrag.
How much RAM is installed?