Defrag and optimize Windows Registry. Quicksys RegDefrag is a freeware utility to defrag registry. It optimizes registry by removing gaps, fragments and wasted space in Windows registry files. It's easy. It's for you. Improve your computer performance with Quicksys RegDefrag 2010. The program does not modify any registry entries. Quicksys RegDefrag is compatible with Windows XP/2003/Vista/2008/Seven