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There can be many reasons such as inadequate RAM to meet your requirements for one. That is why it is good to fill up the System Specs carefully and as completely as possible.
Please tell us what makes you think that the Laptop is slow. Has the pace slackened off after continuous use? As a first step use a good cleaning Program like cCleaner to clear all the accumulated junk. After that defragment the C Drive with a good defragmenter like Puran Defrag, that you can download and install for free from http://www.puransoftware.com/Puran-Defrag-Download.html
To begin with please carry out the above tasks and let us know if the speed has picked up. And please do not forget to fill up your system specs. You will get a lot of other ideas on how to improve matters by reading the tutorial at Optimize Windows 7
Best of luck.