Creating large enums takes a significant amount of time. Moreover this appears to be nonlinear in the number of entries in the enum. Locally, importing a single python file and taking this to the extreme:

 1000 entries - 0.058s
10000 entries - 4.327s

This is partially addressed by https://bugs.python.org/issue38659 and I can confirm that using `@_simple_enum` does not have this problem. But it seems like that API is only intended for internal use and the 'happy path' for user-defined enums is still not good.

Note that it is not simply parsing the file / creating the instances, it is to do with the cardinality. Creating 100 enums with 100 entries each is far faster than a single 10000 entry enum.