Even us Moderators are not privy to all of the changes under the hood. I will ask our Senior Level Engineers on our next Conference Call.
However it is my understanding that the Devs are in the process of addressing the Scan Durations/Hanging. However the architecture of the Scanning process is still being looked at.
It seems during a scan the files scanned is now correct and not showing just the files scanned that could hold a virus.