[TECH-DEBT] 🚀 Performance Optimization: Reduce latency for complex questions (currently ~40s)

[anhmtk]

📊 Current Performance

StillMe currently has ~40s latency for complex questions:

Component	Time	Notes
RAG Retrieval	0.36s	ChromaDB semantic search
LLM Inference	6.43s	DeepSeek/OpenAI API
Post-processing	33.57s	Quality evaluation + rewrite + philosophical depth
Total	~40s	End-to-end latency

🎯 Goal

Reduce total latency to <10s for complex questions while maintaining:

• ✅ Quality and philosophical depth
• ✅ Zero-tolerance hallucination policy
• ✅ Complete transparency and citation

🔍 Analysis

Post-processing is the bottleneck (83% of total time):

• Quality evaluation: Rule-based (fast)
• Rewrite engine: LLM-based (slow - multiple passes)
• Philosophical depth: LLM-based (slow - deep analysis)

Potential optimizations:

1. Parallel rewrite passes - Run rewrite 1 & 2 in parallel where possible
2. Caching rewrite results - Cache common patterns and templates
3. Conditional rewrite - Skip rewrite for high-quality initial responses
4. Streaming response - Return partial results while processing
5. Batch processing - Process multiple validations in parallel
6. Optimize LLM calls - Reduce token count, use faster models for simple tasks

💡 Proposed Solutions

Phase 1: Quick Wins (Target: 20-25s)

• Implement conditional rewrite (only rewrite when necessary)
• Cache rewrite templates for common patterns
• Optimize prompt length to reduce LLM inference time

Phase 2: Parallel Processing (Target: 10-15s)

• Parallel rewrite passes where independent
• Batch validation checks
• Stream response to user

Phase 3: Advanced Optimization (Target: <10s)

• Use faster models for simple tasks
• Implement response streaming
• Optimize RAG retrieval with better indexing

🤝 How to Contribute

1. Profile the code - Identify exact bottlenecks
2. Propose optimizations - Share ideas in comments
3. Submit PRs - Implement optimizations with tests
4. Test performance - Measure improvements

📝 Notes

This is a conscious trade-off - we prioritize quality and philosophical depth over speed. However, we believe we can achieve both with the right optimizations!

Related:

• See docs/PAPER.md Section 4.6 for current performance analysis
• See docs/FAQ.md for performance questions
• See backend/postprocessing/ for current implementation