I have a 460gb HD, with about 350gb free, on my Win7 64-bit home desktop computer, and a 80gb HD with about 50gb free on my WinXp pro work laptop. MBAM quickscan takes about 4 mins on the former, which is much faster than it did prior to v 1.5, and it takes about 45 mins on the latter, which is much slower than before v1.5. So, based on this obviously limited data, one hypothesis is that the speed benefit brought about by the changed scan algorithm of the MBAM update might only be something applicable to Win 7 and/or 64-bit machines, and it might actually adversely effect other systems. So, those who are getting faster/slower scans, what system are you running it on?