I have a few issues as well - its not just the older iPhones. I have an iPhone 6 128gb, less than a year old with pretty minimal usage if I'm honest.
Since updating to iOS9 I have noted a few things that are really annoying and to be honest, ruining the iPhone experience, a few of the main issues annoying me are:
- Lag: swiping between screen. Swipe to unlock. Lock screen camera short-cut all affected by irritating lag/freezing.
-Opening apps: including apps that are optimised for iOS9, I open some and there is a black screen for a few seconds before it will actually open. I've never had that in any other iPhone or iOS before.
- Camera: All modes seem to be affected like this: when i press the shutter button to take a picture, its stalls a bit, sometimes even showing the little 'load' animation on the shutter button itself. The pictures I'm taking are nothing special in good conditions. Panorama pictures are now affected by a really strange 'flickering' is all I can describe it as...it's reminiscent of the effect you get when filming a computer screen or similar - if you know what I mean.
- Spotlight search: often doesn't work correctly when I swipe down on my screen, sometimes the keyboard shows up in landscape as opposed to portrait (?). Also, the home screen behind sometimes doesn't get blurred out.
- Battery: So I work 9-5:30 and I use my phone minimally through out the time I'm at work, maybe for 30/40 minutes or so whilst I'm on my lunch and that will only be for replying to messages, i typically use my computer for things like FB, e-mail etc. When I had iOS8 id would usually end the working day (5.30pm) on about 85 - 90%%. Since iOS9 update, with the same usage, same settings it now drops to around 75% with no extra usage. Further more, the power savng mode, IMO, really does jack.
- Internet connectivity: iOS9 has somehow really effected the internet connectivity on my phone. When at home all my other devices work just fine, no problem but my iPhone with ince getting the update - constantly drops connection.
Just thought id share my frustration, after all, I'm English and love a good moan đ