Have you done any adjustments to your bridles at all? Most beginners to the sport get the notion that the bridles are set up at the factory and should never be touched or you will screw up your kite. This is far from the truth!
Bridles are set from the factory in a "Neutral" position. This is a setting that the manufacturer says should be good for optimum wind conditions. ALL BRIDLES ON PROFESSIONALLY MADE KITES ARE MADE TO BE ADJUSTED FOR THE DIFFERENT WIND CONDITIONS.
A couple of basic generalizations on bridle adjustments:
There are usually two settings that most kite flyers will refer to on a kite bridle setting. Either the kite is set "Heavy" or the kite is set "Light"
A "Heavy" setting usually means that the bridle is set up in a way that the sail is very flat (perpendicular) to the wind. When you launch the kite, the kite will rise up from the initial launch and then kind of hesitate and even fall back down to the ground...like it is to heavy to fly.
a "Light" setting may also be referred to as "To much forward drive" (this is what your Freestylist sounds like in your post). The kite flies forward very fast and is very hard to stall out. This is usually caused when the bridle is set with the nose of the kite more towards the pilot and the sail is not flat against the wind.
Usually, you can adjust your bridle to either bring the nose forward (lighter) or drop the nose back (heavier) for the different wind conditions. For flying in your stated 10+ mph winds, I would drop the nose back so that the sail is standing more upright (heavier setting). This will give the kite less forward drive and make it much easier to snap stall and hold its position without having to run like mad downwind to hold the kite there (you will still need to move, but not nearly as much or as fast). If you try and fly your kite but the wind is to light and the kite just drops back onto the ground like a brick, bring the nose forward to give the kite more forward drive (light setting). Setting your kite somewhat "Heavy" will make it easier to snap stall and work on some of your slack line tricks.
The kites will have a different way of setting the bridle. Some kites have pigtails on the upper leading edge that you can connect to different knots for your settings. Most kites will have a larks head style knot close to the flying line attachment point that you can open up and slide up towards the nose or down towards the (outter wing or spine) to set the bridle. If you inspect your bridle, you should see the adjustment point and on your Freestylist will have a mark on the bridle that you can use as a reference point to make your adjustments. The mark will also let you put the bridle back to the factory setting after adjusting should you ever need to re-start from ground zero.
I hope this info helps yourself as well as others who may have the same questions or need of information as you.
Good luck - Fly - and have fun!!!