If you upgraded to 8.1 you could try running a few cleaning utilities like the windows disk clean and the maintenance utility. If you open disk clean make sure you tick all the boxes although you might see a checkbox for .windows old and it relates to the old windows you upgraded from. If you don't need it anymore then remove it. (you can find disk clean via admin tools in the control panel.
To initiate the maintenance utility open the control panel find the action centre and look under maintenance.
Post back if this doesn't help any..