Are we talking about gybing with spinnakers? If you don't have a spinnaker up and in a strong breeze, be sure not to sheet the mainsail in too much prior to a gybe or when it fills on the new gybe, you'll be in the water before you can say "holy fly swatters batman!".

The trick to smooth heavy air gybes with our without spinnakers is to keep your speed up and don't try to slow down before the manuever. The faster you go downwind, the closer you are sailing to windspeed and the sails will absorb less shock when they switch sides.