Try this, open an admin command prompt and type:
Press enter and you'll see a Disk clean box appear with checkboxes. Check these off although leave anything to with updates unchecked. If you have no need of the windows.old file any more you can remove it by making sure 'remove previous installations' is checked. Once you've finished click ok and the box will disappear. To get the advanced Disk cleaner to run type, again in the admin command prompt:
Press enter and it will cycle. You may find it helps then again it could all be down to the fact you upgraded and a clean install could ultimately be the best solution.
You can also check the Task manager and look under 'Start up'. You may have some apps starting which you don't need and stopping them from starting with windows can make a big difference depending on what it is.