I get really good performance as well.
I think there is a bug in Panda that is killing the frame rate when a projected texture is used along with the shader generator.
There is one bug in this code; if you have an model under the ground it will still show up as a shadow. I suggest using a clip plane on the shadow camera to make everything under the ground invisible. This should not be a common problem though, as I see no reason to place a model under the floor.