Performance with web bundle

[rothsandro]

Hi,

I'm migrating my Eleventy template from Prism (via Eleventy Syntax Highlight Plugin) from Shiki using the markdown-it plugin.

import { fromHighlighter } from "@shikijs/markdown-it/core";
import { createHighlighter, bundledLanguages } from "shiki/bundle/web";

const highlighter = await createHighlighter({
  langs: Object.keys(bundledLanguages),
  themes: ["light-plus", "dark-plus"],
});

markdownIt.use(
  fromHighlighter(highlighter, {
    defaultLanguage: "text",
    fallbackLanguage: "text",
    themes: {
      light: "light-plus",
      dark: "dark-plus",
    },
  })
)

For testing purposes I took an existing Markdown file from the repo, duplicated it 1200 times and then run the Eleventy build:

Library	Build Time	Shiki Setup
Prism	10s	n/a
Shiki (with web bundle)	46s	760ms
Shiki (with 8 langs)	14s	45ms

The Shiki Setup (createHighlighter + fromHighlighter) takes longer the more languages we initialize - which is expected and also acceptable as this happens only once and does not depend on the number of Markdown files.

Shiki with 8 langs is slower than Prism (10s -> 14s) but still acceptable. But with the web bundle initialized the build is way slower (14s -> 46s). Is this really expected? I thought that createHighlighter() already loads the languages (that's why it is slower) and running syntax highlighting should not affect how many languages are loaded (as the number of languages actually used in Markdown files is the same).