In fact the TFastSprite will not be able to be used for billboards like trees, as it is based on the GL_POINT_SPRITE and this is always rotated to the camera and there is currently no way to turn this behaviour off.
But one solution is to use the singlesurface sprite system I'm
working on together with my particle system and to apply VBO on it this should make it damn fast and framerate should firstly drop at around 5000+trees (hopefully, not tested).
But one solution is to use the singlesurface sprite system I'm
working on together with my particle system and to apply VBO on it this should make it damn fast and framerate should firstly drop at around 5000+trees (hopefully, not tested).