Update Page Speed

[Macawls]

Updating a page by calling update_page is slow. More than a minute to remove a sentence. This is not ideal at all.

[Macawls]

Root Cause Analysis

Investigated update_page in internal/mcp/tools_pages.go. Here's why it's slow:

1. Full Markdown Re-render on Every Update

Every call to update_page re-renders the entire markdown content to HTML via renderContentWithErrors(), even if only metadata (title, slug, visibility) changed. The render pipeline includes:

• Goldmark parsing with GFM, footnotes, callouts, embeds
• Chroma syntax highlighting for every code block
• D2 diagram rendering — graph layout calculations + SVG generation for any d2 code blocks

2. Full Column UPDATE

The DB query updates all 12 columns every time, even for a single field change.

3. Two Separate DB Operations

UpdatePage() and SavePageVersion() run as separate operations instead of a single transaction.

Suggested Optimizations

1. Skip re-render if content didn't change — biggest win, avoids the entire Goldmark/Chroma/D2 pipeline for metadata-only updates
2. Batch UPDATE + SavePageVersion into one transaction
3. Skip version save for metadata-only changes
4. Profile D2 rendering — likely the slowest part of the pipeline for pages with diagrams
5. Consider caching rendered HTML and only invalidating on content change

[Macawls]

Implemented Optimizations (commit 07b755b)

Phase 1: Quick Wins

• Skip re-render when content is unchanged — if the AI sends full content but only changes metadata (title, slug, visibility), the expensive Goldmark/Chroma/D2 pipeline is skipped entirely
• D2 diagram SVG caching — D2 compilation results are cached by sha256(source) in a sync.Map. First render is still slow, but subsequent renders of the same diagram are instant (~0ms vs up to 30s)

Phase 2: Async Rendering

• Background rendering — update_page and append_to_page now save raw content to DB and return immediately (~15ms). Markdown→HTML rendering, content_html update, and version save happen in a background goroutine
• Two-phase SSE preview — new PageContentSaved event fires instantly on save. Preview page shows a loading bar + content opacity fade. When background render completes, PageUpdated fires and preview reloads with correct server-rendered HTML
• New UpdatePageContentHTML DB method — lightweight partial update for just the HTML column

Expected Impact

Metric	Before	After
MCP tool response	70-500ms	~15ms
D2-heavy pages	up to 30s	~15ms on cache hit
Preview feedback	1-2s (toast + reload)	Instant loading bar, reload on render complete

Still open

• AI model thinking/generation time (~30-60s) dominates total latency — not something we can fix server-side
• Could explore partial content updates (diffs/patches) in the future to reduce AI token generation
• Goldmark instance reuse for RenderWithErrors (~1ms savings, low priority)