Thanks. I realise "instantaneous" isn't going to happen, but thought it possible that the bluetooth negotiations might just be quicker if the processor was faster , even though only on the phone side.
The situation with my HAs and iPhone 6+ is variable. I use the ReSound SMART app to switch program, streaming source, volume etc. The app has two progress bars for the connection status at the top of the screen.
Most of the time, I open the app to change something and the HAs are already connected and I can do what I want straightaway Occasionally they are not connected and the progress bars show and it takes maybe 2-4 seconds. I haven't noticed any previous history which determines whether they are already connected or not. It is not a simple matter of whether I have recently been out of range of my phone. I can go out of range of my phone e.g. leaving it in a different room, and when I come back in the room I can see the phone wakeup as it recognises and connects with the HAs.
The other delay is incoming phone calls. After I accept the call there is a delay before the caller can hear me. I think this happens pretty consistently every call. It has improved since I got my ReSound Enzos a year ago.
As I said this is not a big issue, I am pretty happy with how quickly they connect. There is an element of justifying getting an iPhone 6s here!