PHPUnit 10 is faster, and the number is smaller than claimed

The release notes talk about a significant speed improvement, and on a suite dominated by database work the improvement is in the part that was never slow.

our suite, same machine, same tests:

  9.6    14m 12s
  10.0   12m 54s      -9%

where the 9% came from:
  test discovery and metadata parsing, which was
  ~70s of the run and is now ~8s

where it did not:
  1,100 tests that each open a transaction against MySQL

The improvement is real and it is in framework overhead, which is proportionally large on a suite of fast unit tests and negligible on one that talks to a database. Quoting a percentage from somebody else’s suite is how expectations get set wrongly; measuring before upgrading takes one command and makes the upgrade’s justification honest.