I was just telling my wife yesterday that if this isn't fixed in 9.2, I'm selling/returning the phone and moving on to something else. For $850, I expect much higher quality from apple and it's disappointing to see them fail to address this issue, even if there isn't currently a fix. I suspect hardware as well, because if there were an easy fix, it would have been addressed in 9.1.
Previous to my purchase of the 128GB 6s on 9/25/15, I had a perfect 64GB 5s. The Touch ID amazed me on that device from day one, even as a 1.0 release for their hardware lineup, and it was solid throughout its two year life. I'm on the beta program and ran both the iOS 9 beta in May this year on my 5s and the final bits release in September on that phone without any unlock delay.
The very day I purchased the 6s, I noticed the unlock/Touch ID delay. I thought it was carryover from an OS that had been restored throughout several upgrades in its life from the 3GS, to the 4S, to the 5S, and now to this phone, so I DFU restored the phone and kept nothing from my previous settings or applications. I simply acted like a new iPhone user and went down the arduous road of customizing back to my tastes, one app at a time. Within an hour of setting up fresh, the Touch ID unlock lag issue came back, just as it was before. I was incredulous.
Being on the beta program, my first thought was, "ok, this is definitely a big issue I'm sure they've already address in the latest beta release" so I jumped back on the beta channel and upgraded to 9.1 beta 1 in hopes of seeing a fix released. There was none. Nor was there on all of the many beta releases leading up to final release of 9.1 or the upcoming 9.2 release (as of 9.2 beta 4).
I visited an apple store on October 30th to report the issue in person and get feedback from a 'genius' on what's going on with other customers or if Apple has released any information internally on it. The Genius had nothing to report but did replace my phone (with another Samsung based chip) after trying to get me to replace my screen. Within 3 hours, that phone was exhibiting the same issue.
I'm losing hope that a fix will be released at all. I've reported this issue 12 times since 10/10/2015 in the beta feedback app with the following case numbers/titles with no response from apple, either by fixing the issue or personally.
10/10 - Touch response intermittent - System Slow/Unresponsive - #1459304
10/13 - TouchID slow to unlock - Touch ID - #1465315
10/13 - TouchID slow to unlock in iOS 9.1 beta 5 - Touch ID - #1465318
10/22 - Touch ID slow to respond on unlock - Touch ID - #1480355
10/30 - Touch ID slow to unlock - Touch ID - #1483627
11/17 - 3 second delay when unlocking iPhone with Touch ID - System Slow/Unresponsive - #1516934
11/25 - Unlocking phone with Touch ID is slow. (4-5 second delay) - Touch ID - #1526291
11/26 - iOS GUI stutters and delays upon unlock - System Slow/Unresponsive - #1493528
11/26 - Unlocking phone from Touch ID after 1 min or more of unuse results in 3-4 second delay before UI is available. - Touch ID - #1506697
11/26 - 4 second Unlock delay with Touch ID - System Slow/Unresponsive - #1518027
11/26 - Phone is unresponsive first 4-5 seconds after awaking from lock - System Slow/Unresponsive - #1522061
11/28 - 3 - 4 second lag from Touch ID unlock - Touch ID - #1502069
Looking back at the submit dates listed above, I don't think they're the dates I actually submitted the cases. I generally submitted at least one case after each beta or public build release while the dates above are heavy on the last two weeks. IE, I didn't submit four cases on 11/26. Maybe it means they're updating case notes on their side and it's the last 'touch' date?
Anyhow, I've never been disappointed in an iPhone over six years (three previous iPhones) and this marks the first time I've lost faith in the hardware and the software that runs on them and am ready to try an Android or Windows Phone. Some sort of communication from apple would help me keep the faith that they're interested in solving this but the silence on this issue speaks volumes to me.
Justifications for a hardware issue: I believe it only affects phones with the 3D touch component (which I could totally do without). It sounds like phones with both the TSMC and Samsung chips have reported this issue and other phones with iOS 9 such as the 5S and 6 series are not reporting this issue so my money's on it being a problem strictly with the 6S line. Hardware could prove impossible to solve with a software fix and why we haven't seen anything in the 9.1 or 9.2 releases of iOS. Apple will be reluctant to acknowledge any sort of hardware problem they can't fix and thus have been quiet about it.
Justifications for a software issue: Touch ID/unlock performance seems to be 'normal' for about an hour after hard resetting or rebooting the phone. I think this is why so many people think disabling/enabling setting X, Y, or Z seems to 'fix' it. They quickly and excitedly post that they've found a fix, only to be disappointed again 1-3 hours later, but don't always update the support thread that it doesn't continue to work. I have tried all purported settings changes to fix it myself (turning off 3D touch, reduce motion, etc.) and have had no luck in the long run. Given that the phone works fine for a time after reboot though may mean that there's something they can do periodically in code to simulate a reboot and prevent the interface from 'clogging up' after running for a bit. Also, the Touch ID sensor seems fine once the phone's been unlocked and is being used with other apps to unlock such as Amazon, Lastpass, CapitalOne, etc. So it seems to be whatever process is 'sleeping' when you wake it up, needs to be more alert and responsive but it may come at the expense of battery on this model. Sometimes the actual unlock is fast with Touch ID but then it hangs just as the screen animation occurs to show the home page or on the first app you try to open so I don't think it's the actual Touch ID sensor but something during the wakeup function.
Does what I've described resonate with you? Are people in this thread seeing it any differently? Keep submitting bugs, calling support, and chatting with the geniuses on this issue. I really don't want to give up on Apple if they can salvage this phone and make it work but I'm quickly losing hope. Thank you.
