when you say "real-time rendering" do you just me doing it quickly?
I have no idea about the current state of real time rendering research but I have a few thoughts on the basis that it isn't a big field of research.
Engine developers are leading the way.
In my experience academic's are not good at writing production quality code and most of the speed ups are hacks or tricks which reduce quality / quantity in a way that the eye doesn't notice easily.
Its also easily parallelized with a gpu. Throw more cores at it, it will get faster.
Who wants to pay for this research?
I'm trying to think of another field which requires real-time rendering which looks good and is currently lacking. Even naval simulators that the Royal Navy use have crap graphics.
Its easy to do crap graphics quickly, who defines what is "good"? Its easier to go for perfection (reproduce reality) and let hardware handle the rest.