Performance issues

[Viicos]

Performance related to stubs generation

As a first workaround:

• Use multiprocessing to run the multiple codemods (see how it's done in bump-pydantic)

If some codemods take too long to run, other options should be explored (as a replacement for LiCST). Preferably CST parsers as well.

Performance related to type checkers

pyright seems to handle it correctly, at least when used with Pylance. mypy should be benchmarked as well.