I have an iPhone 6 running latest iOS.

In the last week or so this problem has come up. Never experienced it before, and definitely haven't made any changes to the phone that would have caused it.

Every time I type anything on the keyboard, the whole phone freezes up. Not permanently, just for 5-10 seconds, and then it finally comes back and displays the last character typed. While it's frozen, it's still recognising taps - if I keep typing when frozen, all of those characters will display as soon as it unfreezes 5-10 seconds later.

Also, if I use dictation, it works until the part where it actually needs to display the text on screen, at which stage is freezes up as normal and does not write what I spoke for the 10 delay.

The phone is nearly unusable in this state as it takes many minutes to compose even the simplest of messages.

What I've tried so far to fix it:

1. Update to latest iOS and hard restart. No effect.

2. Disable "predictive" and "check spelling" and then hard restart. Possibly minor improvement but still essentially the same - maybe a few seconds shorter freeze? Hard to tell, still sucky. Even if it did fix it though, it's not a permanent solution if I need those features.

3. "Reset keyboard dictionary" and then hard restart. No improvement.

After a hard restart, I often think it's fixed because it appears to work fine the first time I test it. But then when I go back to type anything again, it's back to its old unusable self. Seems like a hard restart fixes it for about 30 seconds.

Any advice on what to try next to fix this issue? And any idea on what's caused it?