In my experience there is no one program that can cure all
A good start is to do a full virus scan (make sure you have an up to date antivirus program)
Then use CCleaner to clear junk files from your PC
Then do an antispyware scan using Malwarebytes and Spywarebaster download these from
http://filehippo.com/
Then defragment the hard drive (not if it's a new Solid state drive) using MyDefrag v4.3.1 download from
http://www.mydefrag.com/
Have patience these check will take several hours but will be worth it