My current company is a Python shop, 1M+ LOC. My CI run earlier today completed mypy typechecking in 9 minutes 5 seconds. Take from that what you will.
Ditto, same order of magnitude experience; at least for --no-incremental runs.
Part of the problem for me is how easily caches get invalidated. A type error somewhere will invalidate the cache of the file and anything in its dependency tree, which blows a huge hole runtime.
Checking 1 file in a big repo can take 10 seconds, or more than a minute as a result.
