---
title: "Fast on every run"
summary: >-
  A single static Go binary, no runtime to start. The workspace walk
  runs in parallel, embeds are linted once, and `check` is built for
  the hot path — an order of magnitude faster than Node markdownlint,
  with a CI gate against regression.
icon: zap
link: "/reference/cli/check/"
weight: 6
group: "One engine, every surface"
---
# Fast on every run

Speed is a feature, not an afterthought.

**No runtime cold-start.** mdsmith ships as one static Go binary.
There is no Node, Python, or JVM process to launch before work
begins. Process start time is measured in single-digit milliseconds.

**Parallel workspace walk.** Files fan out across all available
cores. Files pulled in by `<?include?>` and `<?catalog?>` are
linted once regardless of how many host documents reference them —
a large doc set does not re-scan the same prose repeatedly.

**Hot-path design.** `mdsmith check` shares the rule engine with
the LSP server and the fixer. Editor feedback, `git commit` hooks,
and CI all run the same optimised core — no per-surface overhead.

Concretely: a small working set is near-instant. An 18-file
`docs/features` check is ~50 ms. A full check of this whole
repository runs in:

<?include
file: ../research/benchmarks/headline.fragment.md
?>
<!-- Generated by docs/research/benchmarks/gen_fragments.py from
docs/research/benchmarks/data/*.json — do not edit by hand. Re-run
the harness (run.sh) and `mdsmith fix` to refresh. -->
One static Go binary checks 766 Markdown files in about
0.2 s. That is roughly 22x faster than Node markdownlint.
It does more per file than the Rust linters; closing
the gap to the fastest of them is active work.
<?/include?>

These numbers are re-measured each release, not hand-typed. A CI
gate (`check-bench`, modelled on the LSP latency gate) fails the
build if a 60- or 600-file synthetic check regresses past its
budget. See the
[benchmark research doc](../research/benchmarks/README.md) for the
full cross-tool comparison — on the published site this link
resolves to the rendered copy on the `assets` branch, which
carries each release's freshly measured numbers.

See the [`check`](../reference/cli/check.md) reference for flags
and exit codes.