A year or so ago my iPhone 6 was constantly freezing up and was practically unusable. I tried changing literally every setting available in an attempt to resolv

A year or so ago my iPhone 6 was constantly freezing up and was practically unusable. I tried changing literally every setting available in an attempt to resolve it. Wiping it clean and restoring from a backup solved it. I was almost convinced it was a problem with the flash chip as symptoms were exactly what you describe here.