Then something is either wrong with your conception of PRs or whatever process you have been submitted to. PR is asking for feedback from people that already understand the software. It's also a learning place for anyone that is not yet familiar with the part being modified. So you have the author, the reviewers, and the learners. Which is three separate sets of people.

The PR review itself shouldn't take a lot of time (10mn is already a lot), because it's either a small change which is easily understood[0] or it's a more complex one [1] that should have a design discussion thread attached. This discussion is orthogonal to the code itself. Both should have a description good enough for the reviewer to have an idea why the change is necessary before looking at the code.

So a PR is an exchange of ideas around a real artifact, the code. If no idea is being exchanged, then it's merely a gatekeeping activity.

[0] https://cgit.freebsd.org/src/commit/?id=73b1453e6d87f9af4c47...

[1] https://cgit.freebsd.org/src/commit/?id=49a3cbc47f8e721a787e...