Windows 7 is hungry for resources. It features many visual effects that draw heavy on your graphics card and system memory. If your system was slow out of the box, chances are you can easily fix that by turning off superfluous effects.
Go to > Start and type ‘performance‘ in the search field. Select > ‘Adjust the appearance and performance of Windows‘ from the results. The > Performance Options window will open. Under > Visual Effects select > Adjust for best performance. If you would like to retain a nice interface, select > Custom and check > ‘Use visual styles on windows and buttons‘.