Check to see if your phone has a power saving mode that limits the background activity of apps. If you're only concerned with how the foreground app is function

Check to see if your phone has a power saving mode that limits the background activity of apps. If you're only concerned with how the foreground app is functioning, then this would probably work perfectly for you. Also within the settings, you can select what to do with apps that are pushed to the background. It'll be under the developer settings.