iOS 9 now freezes

[logicstudiouser]

I have noticed some bizarre behaviour that has come out of nowhere and occurs randomly on my iPhone:
1. iPhone freezes and sleep/wake button doesn't shut screen off, even after pressing multiple times (have to wait 2 minutes and the phone restarts automatically)
2. iPhone freezes when unlocking with touch ID and sometimes even when entering passcode, it takes iPhone a while to process the login
3. Slow and lags at times in general

It is as if my iPhone has a virus, except all the apps I have are well established apps on app store and I have never jailbroken my phone

Any ideas what the issue could be?

 

[FeliApple]

I'm using iOS 9 in all of my devices. I haven't had such an issue. I don't want to sound insulting, I'm pretty sure you already know this, but every single issue of that nature I've had has been solved with a hard reset.

 

[gaussblurinc]

I see interesting behavior sometimes.

I open FaceTime and press Audio/Video buttons of segmented control on the top left. They don't work and also history list is empty.
Next, I navigate to FaceTime tab in Settings app. This tab has broken animation and also freezes Settings app.
Restart helps to fix it.

I have encountered this problem twice in a last two weeks.

UPD
When I try to dismiss Settings app in this state ( by pressing home button ), iOS doesn't react. After a while multiple events are appearing. ( App animates back and forth from fullscreen to app list ).