Well I've been participating on another thread about the 6s+ lag issues.
I'm experiencing everything the OP has mentioned plus various other issues like:
1. Status bar missing for couple of seconds after unlocking the phone using Touch ID
2. Screen freezes when unlocking the phone with Touch ID with a Live Wallpaper
3. Multitasking is definitely slower
Now I've done everything to try n fix these problems like Setting up as New, Restore from iTunes, Erase Network Settings, Erase Data, etc, etc. Nothing has worked.
When Apple released the iOS 9.1 I thought that would take care of all my problems but to my disappointment it hasn't.
Yesterday I got a chance to compare mine to someone else's 6s+ 64GB and WOW!!! Mine felt like a 6+ compared to the other one as that one screaming all the way, for example mine had a 1-2 second delay when taking pictures using the native camera app. I checked the settings on both the devices, everything was identical. Did a hard reset on both, on the same WIFI network, yet mine was drastically slower than the other one. Call me OCD but this stuff bothers me a lot.