Neither the 2916 nor the 5000 were standalone for this test, but their utilization is generally low. We expected that the round trip timings reported by traceroute would increase linearly with packet size, so we tried a brief experiment. This turned out not to be true. As can be seen in the following graph, time vs packet length graph appears to be two straight line segments with an inflection point at 512 bytes. The results are puzzling and we need to make a number of additional measurements before we can say anything meaningful.
Switches can be either cut-through or store and forward.
Vendors don't see a market for cut-through. This is easier to implement in a store and forward switch, since one does not have to determine how much of the packet has arrived before looking at various fields in it. It is probably not possible to implement extremely low latency interconnects with general purpose network components. However, these are at least an order of magnitude more expensive per port than general purpose technology. Whether this is cost effective depends on the particular application.