To temporarily stop Disk Defragmenter so you can run other programs faster, click Pause. During defragmentation, Disk Defragmenter must restart each time other programs write to the disk. If Disk Defragmenter restarts too often, you may want to close other programs while defragmenting your disk. You can use fragmented files, but your computer takes longer to access them. Disk Defragmenter rearranges the files and free space on your disk.
Files open more quickly because they are stored in adjacent units and free space is consolidated.