My new laptop is two months old, the first day I got this laptop I noticed this but I assumed it was a bug in Windows 8. However I still have this issue today after reformatting and installing all updates.
The problem is that the disk shows 99% usage from an application...
In this case Dropbox, but the usage is never over 2 MB/s; in this case it is 0.8 MB/s.
What can I do about this?

services.msc, hit Enter, find thereSuperFetchservice, double-click on it and change start mode toDisabled, restart computer. And tell us the results. – Jet Jul 04 '14 at 15:37