Overtime all these data become fragmented and affects overall system performance and increases the waiting time for loading programs and opening files.
To improve your system performance you should reduce the fragmentations and compact registry to a smaller size. There are several utilities for defragging registry; Wondershare Registry Defrag is such a tool that optimizes your registry by removing gaps, fragmented and wasted space in windows registry files.
Wondershare Registry Defrag is freeware and supports Windows 7, Vista and XP. You can download it free at source.