Defragmenting your hard drive is an important way to optimise its performance. You could do this with Windows own defrag tool, but it's slow, basic, and lacking in features. If you really want to get the most out of your system then you should look to one of the alternatives, and PerfectDisk is one of the best.
The program doesn't just defragment your files, for instance: it also uses a technology the authors call SMARTPlacement to rearrange them for improved performance and reduced fragmentation in future. PerfectDisk will optimise the MFT and other system files that competing defraggers usually ignore. And the algorithms used are so efficient that your system can be properly defragmented even if there's less than 1% free hard drive space left.
You don't have to wait forever for this to happen, either. PerfectDisk can run in a screensaver mode that means it'll defragment your system when you're not around, so it's always running at its optimum performance. And if for some reason this doesn't work out, then you can select just a few heavily fragmented files and have the program defragment only those: much quicker.
And a range of new features and enhancements includes improved support for SSDs and large drives, a reduction in the resources used when defragging in the background, and a redesigned interface that makes the program easier to use than ever.