I have an ageing 7year old laptop running Windows 7. I played with background defragmenttion in all the current defragger like O&O, Perfectdisk, Diskeeper and found them to be CPU intensive. MST the other hand works very light and uses only idle CPU cycles. I barely noticed its operation. In fact I doubted whether it was doing anything but it always kept my hard disks 0% defragmented. It doesn't have all the bells and whistles that other apps have, but still love how it runs.