Markdown Fast
A faster Markdown preview for VS Code. Drop-in replacement for the builtin, optimized for large / code-heavy documents — TTFP drops from roughly 4.6s to under 1s on a 5MB plan file.
Why it's fast
- Lazy highlight —
highlight.js runs in the webview, and only visible code blocks are highlighted on first paint. The rest highlight as you scroll.
- Viewport-first rendering — the visible viewport is rendered and painted before anything below the fold; the rest is rendered after first paint.
- Token-boundary slicing — the document is parsed once, then split at top-level markdown-it token boundaries; only the viewport's tokens are rendered synchronously. Splitting on tokens (not source lines) means a slice never bisects a fenced code block, list, table, or blockquote.
Same markdown-it pipeline, same keybindings, same syntax highlighting, same scroll-sync as the builtin. Final DOM matches once everything has finished rendering.
Install
From the Extensions sidebar (⇧⌘X), search for Markdown Fast, or:
code --install-extension maaashjp.markdown-fast
Usage
Open a .md file and press ⇧⌘V (preview) or ⌘K V (preview to side).
Make it the default previewer
Markdown Fast and the builtin both register the same commands and view types, so to make Markdown Fast the active previewer you should disable the builtin.
- Open the Extensions sidebar (
⇧⌘X).
- Search
@builtin markdown language features.
- Click Markdown Language Features (publisher:
vscode) and choose Disable. Only this one — leave Markdown Language Basics, Markdown Math, and any other @builtin markdown ... extensions enabled.
- Reload the window (
⌘R / Cmd+Shift+P → Developer: Reload Window).
On first activation Markdown Fast will also prompt to set itself as the default editor for *.md (writing workbench.editorAssociations to your user settings). Without this, opening a .md still goes to the plain text editor; with it, opening goes straight to the rendered preview.
Repository
Source, benchmarks, and the autoresearch loop that produced these optimizations: https://github.com/mash/markdown-fast
Credits
Forked from microsoft/vscode/extensions/markdown-language-features, © Microsoft Corporation, MIT.
