Iphone 6s Keeps Lagging on Basic Features - Almost Unusable. IOS 11.2.6

Hi There,

I am not sure what to do. I've restarted, and restored my phone a number of times, but the issue keeps arising.

When I go to type in a phone number, or any time I open the phone app, the phone freezes completely.

I can't type a phone number in, the lag is over 30 seconds. It is beyond frustrating. Even when someone calls me, I'll press "Accept" and there is a 10 - 30 second lag by the time my phone accepts the call.

I've removed all unwanted apps, and turn off bluetooth, as well as close all apps that were running in background.

This happened right around iOS 11 upgrade. It has basically bricked my phone and is causing so many headaches.