Hi,
For a long time I didn’t had a problem with avast! IS. Recently with version 6.0.1023, I got a fix for WebRep plugin. But lately I found that avast! cause my system to slow down. Mostly I notified this when I’m with Google Chrome. I think it’s due to browser caching. But also other programs (Even MS Paint) are so late to response when I try to open them, as never before. Tried turning off all avast protection modules, then programs are responding as they were before.
I got no other protection modules unless Windows Firewall (Win XP SP3). Use MBAM as On-Demand.
Thankz in advance for suggestions…
Cheers…
Try a clean reinstall of avast.
Thank you for your suggestion mate
BTW I have disabled and enabled transient and persistent cache options from File System Shield > Expert Settings. Now seems there is no lagging on system.
Hopefully your suggestion would work too 
Cheers…