DASH offers an "instant" transaction method known as InstantX or Instant-Send. To take advantage of InstantX withdrawals on Kraken, a withdrawal address must first be whitelisted on your account. Simply, the first successful withdrawal to an DASH address whitelists it for future, faster transactions under InstantX
Consider, however, if the destination doesn’t recognize InstantX payments, transactions may take another 10-15 minutes.
For more information on DASH Instant-Send and InstantX, see the following resources: