So I found out what the issue is. It's Notes on iOS 9 combined with 1GB RAM iPhones.
Specifically, it's when you are dealing with a
massively long note. How do I know? Because I tried typing in a short note and the response was normal.
What this means is that if you do not have the lag I have it's because you do not have a note that is as long as my note. My particular note is so long I can't scroll through all of it on a phone. I have to use the desktop version of Notes to even attempt to school through all of it and even then it takes a couple of minutes. It's the same note Ive been adding to since iPhone 4.
It was never like this in iOS 8 so I know for a fact this is a 1GB RAM + iOS 9 Notes app issue. This means it's purely a RAM + iOS 9 issue.
There is no other reason for this lag period. I'm quite pissed that Apple engineers can't even develop a notes app that can handle long text and keep the performance with iPhone 6! A phone that is only months old!
And to confirm I pasted the entire note into the "Flat To-Do" reminder app and low and behold the lag was gone!
So now is there still a fanboi who is going to tell me it's not a 1GB RAM + iOS 9 issue?
I have attached a shot of the free app I used for testing incase anyone is interested. It seems quite good. If any of you have other recommendations for a cool notes app please let me know. I don't need dates or calendar UI etc. Just customizable text with iCloud syncing.