How does table size impact table lookup speed?
To answer a specific question:

Are benchmarks simply being run in a vacuum and not in production?

Well, yes, pretty much.  If you are running a serious performance test on a specific routine, you deliberately don't run anything else (because whatever else the computer is doing at the time will jitter the timing of the routine you'll looking at, making the results less reliable).  And, yes, this gives an advantage to solutions which use a large amount of shared resources (such as cache space), over how they would perform in a more realistic environment.