highlighting module code re-runs all files when only 1 was modified

[stas00]

Describe the bug

currently if I built the docs already and now are modifying just a single file, a subsequent rebuild completes fast with the exception of:

highlighting module code... 

which runs on all files, and we have hundreds of those.

To Reproduce
Steps to reproduce the behavior:

git clone https://github.com/huggingface/transformers/
cd transformers
pip install -e .
cd docs
make html

then

touch source/examples.md; make html

and it re-runs the highlighting module code on all files.

Expected behavior

It shouldn't need to re-highlight source files that weren't modified.

If this is not possible, please provide a flag/env var to disable this feature completely while doing the bulk of writing and validation of a single document. Otherwise at times it's very difficult to figure out what sphinx is complaining about and requires multiple re-builds until the issue is sorted out and so this re-build needs to be very fast and currently it too slow.

Your project
https://github.com/huggingface/transformers/tree/master/docs

Environment info

• OS: Ubuntu
• Python version: 3.8.6
• Sphinx version: 3.2.1

[stas00]

Amazing! This is so much faster - thank you very much, @tk0miya!