Hardware instancing would probably be the best solution, now I think of it. It's just easier for level-editing if you can group them into bunches of
50 (for example) billboards along a flat plane and then copy and paste to cover the map. I know it's probably better to do grass procedurally,
so I might consider that instead.
Efficient rendering is a higher-level process and very involved. You need to keep updated AABB’s for each object and use them for frustum culling, which can be further improved via an oct-tree.
Once you have a list of things you want to draw you need to sort them by shader, texture, and possibly depth in order to reduce the number of redundant state changes.
Then render them in sorted order. Of course that does no good if you don’t also have a system in place for eliminating redundant state changes. That is if the same shader is set twice in a row, the second time should be a do-nothing call.
Yeah I realised the majority of my work is ahead of me. Was just focusing on this specific problem first.
Thanks for the info people.