If the barb is a permanent fixture, and you want to hardpipe it, then you could get a fitting with a matching barb on one end and appropriate threads or join (If you're going to glue). Then you'd have to get a short piece of vinyl tubing and clamp the two barbs end to end, the tubing may only be three or so inches.
I would guess that if the two ends of the barbs were touching, then it would reduce friction as opposed to having a gap where the waterflow might be turbulent or cavitation might form bubbles.