You will be releasing virtually nothing if you are using a P2P application not on the list the P2P shield will be idle. However if you used another you wouldn't have to remember to enable the protection.
You could if you wish though Terminate the P2P shield, left click the avast 'a' icon, from the window that opens, click the Details... >> button (if one is displayed) and select the P2P shield, click Terminate and answer Yes to the Persist question or it will be restarted on the next boot.