I have a hunch that internally gear hubs don't always operate as efficiently as a single speed, in every gear.
I was looking at sturmy archer 8 speed hubs. The lowest gear was direct, Rpms in is Rpms out. Each higher gear involved more of the hub involving the internal mechanisms, which created drag, through friction, which ate at efficiency.
Some hubs are different, I've read the shimano 8 speeds have less efficiency in 4th gear if I remember correctly. Nuvinci hubs are supposedly even less efficient throughout their entire range, reading I've done suggests especially so at he lower end.
Racers do not use internally geared hubs. I don't think they need they need the range that derailleur setup can take advantage of, I think it is an efficiency advantage (among other things) that drives that decision.
Racers of the sprinting variety use fixed gear, no?
Im not saying efficiency is a necessary concern for the average bicycle commuter, and really I type from a perspective of a reader, not an experienced bicyclist (though I do have some experience on igh, single speed, and derailleur bikes).
If you want to hall ass through that intersection, choose the best gearing, make it fixed gear, and stay clipped in coming to it.
I'm more of the Sunday driver type myself, and would rather wait for a good opening, and consider getting/blasting the loudest horn I could afford, while wearing the brightest outfit and blazing the brightest helmet mount light right into the drivers cabins, then getting back to my Sunday driver attitude. Intersections can be scary, learned that riding motorcycle, seems to translate to bicycles too.