when i tie, i start on one end of a row (usually the right because i'm right handed). I have the top up, like you do in your photo. i usually put my knots on the back. i poke the needle straight up through the layers at the first patch intersection, then straight back down about a quarter-inch away. i usually try to do it on a diagonal across the join. i keep my left hand under the quilt. keeping my hand in the way, i run the thread across and poke up at the next intersection. i use my hand to make sure i have a decent amount of thread running between the joins. i work up and back down at each intersection all the way across ... always using my hand to keep the thread slack between joins/stitches.
i repeat this process across all the rows. when i'm done, i flip the whole thing over. i cut the thread between the joins/stitches and then i tie the knots.
if you want the knots on the front, you'd keep the "slacker hand" on the top, of course.
it's still a slow process, but i can get the whole thing done in a lot less time doing it this way.