There are 2 non deletable comodo entries in the registry :
1/Comodo firewall prohelper driver.
2/Comodo firewall prosandbox driver. Other than that,no other Comodo residues in the system.
Other than slow booting, there is no additional noticeable slowdown, but I wouldn`t want it to get there if I can help it.
I have tried to disable Avast`s booting with Windows, through:config,services,ccleaner and some other programs I have and..... it still boots, the only way to disable it would be to delete the program! this AV rocks!!!