Thanks Henrick..

If the array transform only takes call it ~5ms per generation then at 15hz it's using 75ms in a second.
Roughly equivalent to one extra generation per second. Getting close to not much return for our efforts..

Do we think we can directly evaluate the Neopixel array with it's weird layout.. ?

I'm going to set my display up with some timing pins today and have a fiddle about.

Thanks for all the interesting replies.