Use of the `:file-mapping` to `check-ns-info` now increases run time by a good factor of 5. By memoizing the conversion of types into strings, we can reduce this to a factor of 2. This will also reduce memory consumption, as multiple entries for the same symbol will now contain references to the same string, rather than copies.
I'm thinking of providing the user an atom instead of a map which will be updated when necessary.
Moving to a different approach, declined.