... short answer, trimming the kite 'cause its being choked. Any kite does the same when over sheeted to some degree, but in my experience it happens especially bad when in light winds.
I would guess that if your taking the 2009 Rhino 16m, its light winds. Do the same oversheeting at the other end of its wind range and it won't happen. I've tried other kites and the same thing happens no matter what brand, pull too much and they will back down and turn slower. The trade off is if you design it out you loose some of the raw power it can develope. Its all a balancing act, pros and cons.
There are a few solutions which can fix it, the most obvious one is trim the depower strap 1/4 down, especially at the low end of the kites range, then as the wind picks up, let it go and when wind picks up even more, start trimming again.
Next is move the steering lines on the leader lines of the bar so that you lengthen the back lines (ie the connection under the floats).
The last one is check your line lengths. Since I'm heavy I tend to stretch the front lines well before most other people so the trim of the kite is out of wack. Once all lines are the same length, the problem is made better. As an example, I hadn't checked my lines on my Core 17m lines for approx 9 months and found the kite was getting progressively harder to go upwind and seem to be slower turning than I remember, alot slower through the air. I checked my lines and low and behold, the front was 25cm longer

Fixed them and the kites performance was back. Its amazing how I see people put new lines on a kite and wow at the fact that it feels new again (which I've done too btw).
Anyway, just a few ideas to think about!
cheers,
Robbie