Ah! This is even better. It led me to finding this:
http://icl.cs.utk.edu/hpcc/hpcc_results_lat_band.cgi
I do believe I get it. Now to find out what kind of applications are greatly benefited from this.
Thanks HN! You always make me dig in and learn new things!
Edit: It was "MPI latency" that led me to that result, by the way.