On a web-app, a fixed footer creates a performance issue, as the response and sensitivity is not quite as good as native app. But we have some important controls at the footer level like adding items to the list or submitting the form. So, it is a dicey decision for us, whether to have a fixed footer or not.
Please let me know if there is a convincing study or analysis already done on the same, let me know if more information about my specific case is required.
Edit: As one of the fellow expert have suggested, I need an alternative to footer for my context where currently the footer that I have in my app has two important action buttons. Please let me know if there is any alternative possible