Defer importing ens._normalization to speed up web3 import by 27%

[szemate]

What was wrong?

As of version 7.0.0-beta.2 the import web3 command takes 375 ms to run*, which is quite long for a library import operation. This affects the usability of command-line tools built around web3.py, where import times are critical.

How was it fixed?

By deferring the import of ens._normalization until the first call of the ens.utils.normalize_name function, the execution time of import web3 is reduced to 275 ms* i.e. by 27%.

Todo:

• [ ] Add entry to the release notes

---

Details

Profiling* showed that the ens._normalization module performs two lengthy operations at import time:

• Loading ens/spec/normalization_spec.json that is 3 Mbytes in size takes 7% of the total web3 import time
• Executing the _extract_valid_codepoints() function that performs transformations on the loaded data takes 16% of the total web3 import time

These are very costly operations to perform at every single import, with the sole purpose of initializing the ens.utils.normalize_name function.

*: Measurements were taken with timeit and pyinstrument on an AMD Ryzen 7 machine with M.2 SSD using Python 3.10.12:

   >>> timeit.timeit("import web3")

and

   $ pyinstrument --show-regex '.*(eth|web3|ens).*' -c 'import web3'

[kclowes]

Just kidding, looks like I/maintainers can't add to your PR. Once you add a newsfragment I can merge. Thanks!

[szemate]

Newsfragment added, thank you!

[kclowes]

Thank you!