[Feature Request]: Improve the rendering files speed, on web interface and application for AFFiNE

[6im0n]

Description

When editing large documents in AFFiNE, the typing experience becomes very slow. Even adding or deleting a single character causes visible lag: sometimes several seconds making it very difficult to type or edit smoothly.

What counts as a “large” file

Files that include:

• More than 2,000 characters (for example: long notes, articles, or documentation)
• Multiple code blocks, images, or mixed block types
• Heavy layout structures with nested blocks

Such files are particularly slow to open, scroll, and most importantly edit.

Current Behavior

• When typing a single character, the entire document is re-rendered instead of only the modified block.

• This triggers:

  • Typing delay / input lag
  • High CPU/GPU usage
  • UI freezes (especially on the web interface)

• The issue is reproducible both online and offline, and worsens with document size.

Example symptom:

=> Typing in a long note (with code blocks and images) introduces ~1–2 seconds of delay after each keystroke.

This makes AFFiNE nearly unusable for writing or editing technical content.

https://github.com/user-attachments/assets/19ca3a9c-cb1d-475e-9e78-ecc6d7d6cffe

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Proposed Solution

Implement incremental or viewport-based rendering, so only relevant or visible parts of the document are updated.

Possible improvements:

Biggest improvement effect :

1. Incremental re-rendering - update only the affected nodes when editing.
2. Viewport-based rendering - render only blocks visible in the user’s viewport (lazy-load the rest). (Explain here #13616 )

Some interesting improvement (for future) 3. Memoization and caching - logic to skip unnecessary DOM updates. 5. Block-level change detection - isolate text editing operations from full layout recalculations.

Use case

A user opens a long Markdown or note document containing:

• Several paragraphs (2K+ characters)
• A few embedded code blocks and screenshots

When typing a single letter:

• The full document re-renders
• CPU spikes for ~2 seconds
• Input lags and the cursor freezes momentarily

This destroys typing flow and productivity, especially for users writing long technical content.

Expected Outcome

• Small typing latency, even for long and complex documents
• Smooth scrolling and editing in all modes (web & desktop)
• No UI freeze when inserting or modifying text
• Faster overall document load time

Anything else?

No response

Are you willing to submit a PR?

• [ ] Yes I'd like to help by submitting a PR!

[affine-issue-bot[bot]]

Issue Status: 🆕 *Untriaged

*🆕 Untriaged

The team has not yet reviewed the issue. We usually do it within one business day. Docs: https://github.com/toeverything/AFFiNE/blob/canary/docs/issue-triaging.md

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