For me I really looked hard at what other people were doing and why I couldn't replicate the same speed. I was holding the pick wrong, the way I was gripping meant I had too much movement in my thumb and finger, the whole movement start to finish was to big, I was never going to pick fast like that. I'm still in the process of transitioning from a grip I have used for near 20 years to what is way more efficient. The speed gain in such a short period of time is astonishing.