Whenever I run a JS test locally, I see this taking about five seconds:

# Fetching feature flags...

From the message I assumed this was talking to a web service, but it's only looking at local files, so I think this can be faster.

There are a few hundred YAML files it's parsing, but only a handful actually contain feature flags:

arm ~/mongo$ git ls-files src/ buildscripts/ | grep '\.idl$' | wc -l
464
arm ~/mongo$ git ls-files src/ buildscripts/ | grep '\.idl$' | xargs grep -l feature_flags | wc -l
17