> the best network I’ve ever benchmarked was AWS and measured about 55µs for a round trip
What is "a network" here?
Few infrastructures are optimised for latency, most are geared toward providing high throughput instead.
In fact, apart from HFT, I don't think most businesses are all that latency sensitive. Most infrastructure providers will give you SLAs of high single or low double digits microseconds from Mahwa/Carteret to NY4, but these are private/dedicated links. There's little point to optimising latency when your network ends up on internet where the smallest hops are milliseconds away.
> There's little point to optimising latency when your network ends up on internet where the smallest hops are milliseconds away.
That's just plain wrong. Lower latency always improves everything. Not just responsiveness, but also bandwidth! Because of TCP slow-start and congestion control algorithms, lower latency directly results in higher throughputs.
Not to mention that these latencies add up, which is especially important with chatty microservices applications. Don't forget that typical TCP+HTTPS connections require something like 5 round trips, and that's assuming that the DNS record is already cached! Add in firewalls, load balancers, proxies, side-cars, ingress, and who knows what else, suddenly you're staring down the barrel of 15 millisecond latencies before the data can exit the data centre.
The threshold for "instant" response is 16.7 ms end-to-end, including refreshing the HTML DOM and painting pixels to the screen.
Google and AWS knows this, which is why their data centre networking have ~50µs latencies, some of the best in the industry.
Everyone else: "Nah, don't bother!"
I think you're getting pissed of at a strawman. Everyone obviously _care_ about latency. All things equal, better latency always makes things better, there is no arguing with that.
Yet, that doesn't mean latency is at the same priority spot on everyone's list. If you're using TCP on internet, you have already put latency far down in your concerns. That doesn't make you _not want_ better latency, but that does make it a _nice to have_.
There's no obvious shortcut to latency that doesn't involve either loosing on reliability (not requiring ordered messages, not re-requesting dropped messages), or loosing throughput (not assembling small messages on bigger ones), or limiting yourself to private links.
If you do all the above (as in TCP over the internet), then you've made no sacrifice for latency over throughput and resiliency, which to me makes latency a nice to have, but certainly not a primary concern.