Ummmmmmmmmmm. Comodo just had an update to correct cpu usage. Also with Windows 7 or 8 you no longer need a 3rd party firewall. Dont blame Avast. I have installed Avast with Windows Firewall on hundreds of pc’s including my own with no issues at all. As in matter of fact it was a list of 200+ bugs. Have you used something like Process Explorer to assure exactly what process is consuming your CPU? Can you show us a screen shot of Avast eating up your CPU? These are the problems which occur when people add extra layers of security. Did you excluded ALL the Comodo processes from Avast? Did you excluded the Avast processes from Comodo? Also Avast has a BB which can conflict with D+.

http://downloads.comodo.com/cis/download/updates/release/inis_2001/release_notes.html