The battery drain issue discussed above has already been fixed, so this will be caused by something else.
The question is why the app crashes and what makes it restart - whether it is a bug or whether you are using some battery saver, cleaner or task killer, which keeps killing the app. Repeated restart might cause a higher battery consumption - please check for any app or feature, which could behave as described above, and whitelist the Avast app, it should help.
If it doesn't, please let us know, whether the problem occurs even after updating your app to version 6.10.7, thanks.