Go to Start>Control Panel>Internet Options.
Near the centre of the card that appears are two buttons, side by side labelled Delete Cookies and Delete Temporary Files. Click on the Delete Cookies button and then click OK on the small card that appears at the top. You may have to wait a short time For the clearance to take place but then click on Delete Temp. Files and repeat the ptocess of clicking OK.You`ll have a slightly longer wait here, but once done you should have improved your PC`s speed.
Others, more knowledgeable than me, will be along to help further.