Laptop become very sluggish.

My laptop is a Alienware model M17X10 and is very capable of browsing through chrome links but it in short it will be slow at loading pages or executing and then at a point of time after its been running a while it might be fast and return to being slow shortly after. I'm stumped on a solution for this so I would love some help. I do not believe it is a infection; I have malware,spyware,and a active virus shield i bought and i also have cleaned the registry to the laptop but hey i could be wrong so I'm open to suggestions because I know the computer is capable of loading pages,streaming,etc. much faster.

Also my internet connection is capable of handling multiple computer but my alienware is the main pc active.