Cycles BVH "duplicates"

I’ve got a scene with a lot of geometry, to the point where my 4 gig card will run out of memory sometimes. Many things in the scene are sharing mesh data, which I have verified (a change in one propogates to all). Is this a case where the BVH is supposed to load this shared data into the BVH only once? When I watch the phase of building the BVH, the percentage next to “duplicates” never increases above 0%. Is this an indication that this optimization is not happening? If so, is there a setting I’m missing to make this happen? I can’t figure out if the optimization is already happening, or if it’s even supposed to in this case.

Linked copies are only instanced if they don’t have modifiers. If there are modifiers, Blender can’t know whether each instance actually has the same output geometry or not. Instancing on linked copies isn’t something you should rely on, it’s a nice optimization sometimes, but if you need a copy without the RAM hit, use duplis or particles. Those are always instances. (dupligroups or easiest if you just need several free-floating copies).

I do have modifiers on pretty much everything, but they’re the same modifiers with the same parameters, so they should produce the same output. I was hoping the BVH building would recognize that they’re the same and share them, but that’s OK. I’ll see if I can make duplis or particles work for my scene.

Thanks for the help.