Timing has more importance than blazing speed although it's nice to have both. Three guys who come to mind are Tom Spear, Tony Turner, and Mark Crowell. (Am I showing my age?) I didn't consider any of them blazing fast, but they knew how to time a hole. Even when I was blocking them well, I never felt comfortable, knowing it was just a matter of time before they would figure me out.
I consider knowing your opponent more important than blazing speed also. As for attention time, if you're having trouble holding the ball, then executing, try setting up the ball and closing your eyes for 5-7 seconds before you start watching the defense. Mix that with your occasional 2 second shot.
At my age, my biggest problem other than lack of playing is losing focus and slipping off into a day dream. That, and setting a bait and then closing it about 2 seconds after the ball has gone past. Funny thing is...I still think I can play.
Don't lose faith when higher ranked players smoke you. That's what makes them higher ranked players.