This sample scene shows how the Cache Node from the db&w Tools can dramatically speed up rendering times.
Have a look at the LED surface, which contains a complex nodal network to instantiate the LEDs. The Cache Node is used to speed up repeated calls to the, computationally expensive, raytrace function.
In this case renders with the Cache Node are roughly 5 times faster than without.
Many thanks to Mariusz 'pYo' Skrzypczynski for making this scene available.
Please note that it requires DPKit from Denis Pontonnier to render properly.