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SSE streaming optimization — batching char-by-char events and debouncing React re-renders for Crok AI chat performance
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| name | wsh-sse-optimization |
| description | SSE streaming optimization — batching char-by-char events and debouncing React re-renders for Crok AI chat performance |
Optimizing Server-Sent Events (SSE) streaming where character-by-character emission causes thousands of events and React re-renders, destroying TBT scores.
Use this skill when the Crok AI chat SSE endpoint streams individual characters, causing excessive client-side re-renders.
Instead of emitting one SSE event per character, batch into word/sentence-sized chunks.
// Before: char-by-char (thousands of events)
for (const char of response) {
res.write(`event: message\nid: ${messageId++}\ndata: ${JSON.stringify({ text: char, done: false })}\n\n`);
}
// After: chunk-based (tens of events)
const CHUNK_SIZE = 50; // characters per chunk
for (let i = 0; i < response.length; i += CHUNK_SIZE) {
if (res.closed) break;
const chunk = response.slice(i, i + CHUNK_SIZE);
const data = JSON.stringify({ text: chunk, done: false });
res.write(`event: message\nid: ${messageId++}\ndata: ${data}\n\n`);
}
Impact: Reduces SSE events from ~5000+ to ~100. Each event triggers an EventSource onmessage callback, JSON parse, and React setState. Reducing events by 50x dramatically cuts TBT.
The existing useSSE hook concatenates text via onMessage callback. It already handles multi-character chunks correctly since onMessage does prevContent + data.text. No client changes required if the server sends larger chunks.
| Pitfall | Symptom | Fix |
|---|---|---|
| Chunk size too large | Response feels "jumpy" instead of streaming | Use 30-80 chars, balancing UX and performance |
| Breaking mid-UTF8 | Garbled characters | Use Array.from(response) to iterate by codepoints, then batch |
| SSE format issues | Client receives partial data | Ensure each res.write is a complete SSE event |
| Change | Visual Impact | Mitigation |
|---|---|---|
| Faster response delivery | Chat messages appear faster but same content | None needed — VRT captures final state |
| Text chunking | None — final text is identical | Verify final content matches |
crok-response.md) containing code blocks, math formulas, tablesreact-markdown + rehype-katex + react-syntax-highlighter to render each updatesetContent() call triggers full markdown re-parse and re-renderCrok AI chat rendering optimization — SSE debouncing, ChatMessage memoization, Markdown re-render prevention
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Lazy loading modal containers and route components to reduce initial bundle size — CrokContainer, NewPostModalContainer
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