Hey guys, thanks for your feedback - I'll reply to as many of the above posts as possible.
Battery draining
Inthebathprobably thanks for the detail - if you tap the battery percentage, it should show the amount of time the app has been open, could you check and let me know - it would be useful to check the app is performing as expected. We are releasing some bug fixes shortly that may be causing the issue (we haven't seen the same battery-draining bug, so it's difficult to confirm).
iOS 10 does in general use more background features, so I expect batteries will not perform as well, unrelated to the Mumsnet app.
Performance of Talk App vs Talk mobile web
One of the reasons we provide an app is that the performance is more efficient than the web because data is cached and does not need to be reloaded all the time - this means the battery life should last longer than the web. However there can occasionally be bugs in the app that use unnecessary data and cause the battery to drain faster. It is my eternal challenge to improve the performance, and make the Talk app perform better - so your feedback is super helpful!
Location services
Mumsnet does not use/track/access your location at any time. If we ever did, we would explicitly ask for your permission (Apple require that every app does). The Based on your current location suggestion is not triggered by the Mumsnet app, but a suggestion made by Siri. Your phone records when you use all of your apps, and suggests those apps to you when you enter locations that you typically use those apps.
If you'd like to turn off this iOS feature, go to Settings > Privacy > Location Services > Turn off the Siri location permission.
We'll continue to monitor this situation and fix anything dodgy we see, thanks guys!