User blog comment:SunriseDaisy/Kinda Sorta Maybe Possible Leaving ... In a Way/@comment-3180503-20120515231015/@comment-1874176-20120516144211

If you work with your computer for a longer time, data on the hard drive will become fragmented. They are spread ALL over the hard drive and thus, the computer needs more time to find everything it needs and gets slower.

Defragmentation fixes that; it puts all the fragmented data back together and puts everything in one big block, so the system can find all the stuff more easilyy because it doesn't have to look EVERYWHERE on the hard drive, but just in one area. You should do that every now and then.

Since I don't know what system you have and I only know the German names of everything, I can't really help you, but by using the search function (or google), you should find it.