Play with relaxed, free, and regular breathing. I have had to work with several of my students on not holding their breath during fills and solos.

When you hold your breath you cut off the flow of oxygen to your muscles, causing tension which ultimately results in "rushing" the fill. Your muscles know that you will breath again on the down beat and they try to finish up the fill or solo and get to "one" quickly so they can catch a breath.

Timing is the life of the drummer, your timing must be solid. Practice breathing relaxed, regular breaths as you practice fills. It can be very helpful to talk while your practicing to help your body remember to keep breathing. Singing is good, if you can't sing try speaking the lyrics to your favorite song. Just remember "the trick is to keep breathing"