Right on Richard! I've probably done "DA" more times than anyone else in the world and everytime I do it I'm faster and better at locating the letter cards than the time before. That being said, let me give you a couple of hints on how to cut down on your "search time". When you are talking about the two Jokers and what they tell you about the "soul mate" card use that time to visually locate the position of the first two letter cards in the face up spread (remember in most cases there are at least two cards for every letter so you can find one of the two rather quickly). You can stretch the time here by carrying on a dialog with your volunteer, asking them if they know what these two cards (the Jokers) tell you and then waiting for their reply. If your not too obvious the search for the first two cards will go unnoticed by spectators because they're concentrating on the Jokers. If they should happen to notice it will look to your audience as if your just perusing the spread. Now you are already two cards ahead. As you draw the first and second letter cards and make a brief statement about each you visually locate the third and fourth letters in the spread. Pull those and your done. This is exactly what I do in every performance of "DA" and it speeds up the process dramatically.
Another tip. Take the cue Joker and read it over about 10 to 20 times silently to yourself. You'll be suprised at how much quicker you'll be able to find the letter/card combinations on the Joker. Familiarity breeds success.
Finally there are some tips on the web site www.deepastonishment.com
that will help you divert those who say your just looking for the card that's missing. The "Miko" presentation is one. The "Rod's Mnemonic" is another once you've become proficient with it. The "card reading" presentation is another as it gives you more logical time between draws.
I hope that these suggestions help. If you would like to discuss this further PM me or email me from the web site.