It's not such a big deal compared to pip for a typical python package, but a couple of use cases where the speed is a nice feature are tool running with uvx and inline dependencies in scripts - you'll still see something is installed the first time you run the tool/script, but usually it's fast enough to not notice.

One could also make a comparison to another popular tool, conda, which is glacially slow, but that would arguably be unfair since conda does things uv doesn't.

More generally, it's still a nice thing, though. It's just a little less friction. Even a few seconds slower can nudge you towards different behavior