that is " disk defragment" . i do it twice a year.it is so simple and so effective.
there are three ways to do it.you can choose one of them.
1, start-----type "defrag"------disk defragmenter.
2.start ----- programes----------disk defragmenter.
3,control panel------------------disk defragmenter.
to you ,it may not be new. to me, it is so helpful. but bear in mind , it may take a few hours to finish though.i did it before going to bed.