There's a new build of Diskeeper 2010 available that includes the following fixes: Performance improvements in InvisiTasking related to 8+ core systems and eliminating unnecessary context switching. Fixed I-FAAST measurement that would fail on some busy systems and consequently keep getting rescheduled. Improved defragmentation process [...]
InvisiTasking technology, which can be found in all of Diskeeper Corporation's publicly available products, is much more than a simple method hoping to take advantage of a computer's idle time and/or adjust I/O priority; it's an advanced processing technology. Due to it's truly unique and innovative design, InvisiTasking [...]
Find out (a little bit) more here at Microsoft's Virtualization Partner site.