[...] COMPUTERBILD (Issue 11/2005) copied a severely fragmented Windows XP partition PII 1 to 1 onto eight identical 37 Gigabyte hard disks. This meant that every tested defragmentation program had respectively one hard disk to defragment.

The file structure of each drive was a mess: No single file was saved contiguously. In one case, a 3.42 Gigabyte-sized file was save on the hard disk in 32,591 different fragments.

All tests of every hard disk began with a speed test of the fragmented Windows XP partition. Then the disks were defragmented using the different software solutions. For every test program, COMPUTERBILD timed exactly how long it took to completely sort out all 29 Gigabytes of saved data on each disk. Afterwards, speed tests were run on all of the hard disks to compare. [...]

Yes, it really is true: Defragmentation programs can really make a computer faster. There are, however, differences to consider: A few programs were only able to slightly increase hard drive performance; some even caused more harm than good.

Speed
Those who regularly tidy up their computer save time in the long run. One example can be seen while video editing. In this case, it was found that users could potentially reap performance improvements of up to 65 percent. "O&O Defrag V8 Professional" was the most effective in optimizing the computer and was the easiest to use.

"Diskeeper 9 Professional" and the native Windows XP defragmenters were the fastest in cleaning up the hard disks. Their results, however, were not so impressive: In their tests, wait times for video editing or the loading of large image files did not improve after the hard disks were defragmented. Even the time it took to burn a DVD remained the same.

Features and Functions
"O&O Defrag V8 Professional", "Diskeeper 9 Professional", and "Norton System Works 2005" offered best features. Some of these included the scanning for disk errors and excellent scheduling functions. Such functions allow hard disks to automatically monitor and optimize themselves when disk fragmentation sharply increases.
[...]

Conclusion: Would you like to make your computer up to 50 percent faster? Our Test Winner, "O&O Defrag V8 Professional", was even able to increase performance by up to 65 percent. Other programs, like the Windows XP defragmenter, brought almost no improvements.