When building aiohttp from source, there is a pure Python parser used by default. For better performance, you may want to build the higher performance C parser.
To build this llhttp parser, first get/update the submodules (to update to a
newer release, add --remote):
git submodule update --init --recursive
Then build llhttp:
cd vendor/llhttp/ npm ci make
Then build our parser:
cd - make cythonize
Then you can build or install it with python -m build or pip install -e .