I am now a happy camper!
1) I removed Spyware Doctor via Add/Remove software (my subscription was due to expire soon).
2) I Rebooted the computer
3) I ran JV16 Power Tools registry cleaner
4) I re-installed Avast 5.0.545 free edition
5) I re-booted the computer
The problem I reported when the UI is open with AvastUI.exe is no more!
Avastsvc.exe no longer sucks the life out of my cpu:)
BTW, I was able to leave MBAM installed since it is on demand.
Thank you all for your help!:)