Is S3 slow or fast? It’s both, as far as I can tell and represents a class of systems (mine included) that go slow to go fast.

S3 is “slow” at the level of a single request. It’s fast at the level of making as many requests as needed in parallel.

Being “fast” is sometimes critical, and often aesthetic.

We have common words for those two flavors of “fast” already: latency and throughput. S3 has high latency (arguable!), but very very high throughput.