File fragmentation on disk significantly slows down the file access (read/write) speed, especially in working environments where source code libraries and compilations are frequently updated. So defragmenting software is one of the common tools that computers must use. There are so many defragmenting programs in the market - commercial, free, or open-source. Among them, Diskeeper and PerfectDisk, both with a long development history and solid technologies, are recognized leaders - any other similar applications pale by comparison.