It's not just on your system, I've been experiencing the exact same issue since version 2.03. Tried upgrading to 2.05 yesterday, same story, and once again I've had to revert to version 2.02 in order to get decent speed. No idea what might be causing this problem but I hope the developers will address it in a future version. Defraggler has become pretty much unusable on Windows 7 x64.