re-use the matrixes across frames

[davidedc]

seems like as matrixes are used across frames, and pushed and popped within a frame, they are effectively created anew and destroyed.

It's probably worth to optimise that and keep a bucket of reusable matrixes. Maybe making the mechanism quite modular so you could switch it off or delete it altogether if you change your mind in the future (or if you want to get a build without that particular feature).