[andreyv]

Autoconf can use cache files [1], which can greatly speed up repeated configures. With cache, a test is run at most once.

[1] https://www.gnu.org/savannah-checkouts/gnu/autoconf/manual/a...

[fanf2]

Sadly the cache files don’t record enough about the environment to be usable if you change configure options. They are generally unreliable.