I am again trying to get some working shadowmapping and am further than I ever was before.
I have working Parallel Split Shadow Maps which can easily progress to a combination with LispSM, if I get the math behind it. The shadows are soft using Variance Shadow Mapping.
So far I am really happy with my results but my fps is realy very low (35fps in a simple level) with only three splits, which should be enough for a high quality. I guess this has to do with ineffective view frustum culling caused by my own lightviewmatrices.

Is there any "simple" way for me to improve this? If not, could you may mention your ideas on what to do? Because like it currently is, I don´t see a way usable outdoor shadowmapping.

Thank you!

(3 splits, 1024*768 which is not what I want, but I forgot to make the zbuffer fit and thus it currently is like that)