Norton Internet Security 2009 Scan speed

Hi all… first post here… iv tried searching for my issue but everyone seems to be having the opposite issues… 


Im running NIS 2009 for MAC OSX latest leopard version, on a Macbook pro 2nd gen 2009 version and when i used to complete a full scan of my computer it used to take a few hours to complete scanning 600 odd thousand files, iv updated yesterday and did a scan today and it took about 5 minutes to do the same job.

I haven’t changed any settings on the norton antivirus program and it is set to scan all compressed files. Additionally i have also reset the computer, is this normal or a program corruption of some sort which i should uninstall and then reinstall?