Improve Windows 8 and 8.1 performance by optimizing your drive..

1. Open Optimize Drives by swiping in from the right edge of the screen, tapping Search (or if you're using a mouse, pointing to the uper-right corner of the screen, moving the mouse pointer down, and then clicking Search), enteringDefragment in the search box, and then tapping or clicking Defragment and optimize your drives.
2. Under Status, tap or click the drive you want to optimize. (The Media type column tells you what type of drive you're optimizing.)
3. To determine if the drive needs to be optimized, tap or click Analyze.  You might be asked for an admin password or to confirm your choice.
   After Windows is finished analyzing the drive, check the Current status column to see whether you need to optimize the drive. If the drive is more than 10% fragmented, you should optimize the drive now.
4. Tap or click Optimize.  You might be asked for an admin password or to confirm your choice.
   Optimizing a drive might take anywhere from several minutes to a few hours to finish, depending on the size of the drive and degree of optimization needed. You can still use your PC during the optimization process.