When teaching recall, we want to be sure that our dog knows that time is of the essence. The faster they respond, the better. Once your dog has become fluent in your recall (meaning they're performing it reliably when you ask, within about 10 seconds of you asking), you can start using this technique to increase the speed with which they respond to your cue. 

• Cue your recall
• Immediately start counting in your head (1-Missississppi, 2-Missississippi, 3-Mississippi...)
• The moment your dog responds to your cue, note the length of time it took. 
• If your dog responded within 1-, 2-, or 3-Mississippi, you're going to make a big deal! This is Fine Dining. Happy-talk right away and dole out 1-2-3-4-5-6 treats, one after another, while telling your dog what an amazing job they've done in a happy tone. Avoid petting them - dogs don't find this reinforcing during training exercises, generally speaking! Let the food speak for itself! 
• If your dog responded within 4-, 5-, or more Mississippis, you're going to say "good job" and feed one treat. This is Fast Food. 
• Over time, you're going to pay more for faster responses, so responses within 1-2 Mississippis will get Fine Dining, and anything longer than 2-Mississippis will get Fast Food.
• Then, get really picky and only responses within 1-Mississippi will get Fine Dining. 

This should have your dog responding in lightning speed in no time!