The biggest problem may be in the EDRE_ADSingle.vi which you did not post. That VI gets called 16 times for each iteration of the loop. How long does it take on each call? Is it doing anything which does not need to be done on each iteration, like initializing the external device?
Other things which may slow you down: Writing to file can be slow. You do it twice in each iteration of the loop. Moving the file writes to a parallel loop may allow the acquisition to run faster. You are doing the the same thing many times. Make subVIs. Use arrays and for loops. Avoid coercion dots. Move indicators to a parallel loop - writing to the display can slow the loop.
The Producer/Consumer Design Pattern is an example of how to use parallel loops for something like this.
Lynn
