# issue-22-performance-documentation: Update PERFORMANCE.md with comprehensive results

## Description
Completely rewrite PERFORMANCE.md with comprehensive performance analysis including baseline measurements across all modes (binary/daemon/cached), statistical confidence intervals, stage-by-stage profiling breakdown, and variance analysis. This documentation validates the 50-100x speedup claims with empirical data and provides reproducibility instructions.

## Architecture Reference
Read architecture.md Section 6.5 (PERFORMANCE.md Update) for:
- Complete document structure with 10 sections
- Baseline measurements table format with 95% CI
- Stage breakdown table from profiling data
- Variance analysis with CV < 10% validation
- Speedup interpretation and bottleneck analysis

## Interface Contracts
No code interfaces - documentation only.

**Input Sources:**
- Benchmark results from benches/binary_subprocess.rs, benches/daemon_mode.rs, benches/cache_performance.rs
- Profiling data from `pyrust -c "2+3" --profile` and `--profile-json`
- Speedup validation from scripts/validate_speedup.sh

**Document Sections:**
- Baseline measurements table (5 modes: library, binary, daemon, cached, CPython)
- Stage breakdown table (5 stages with time/percent)
- Variance analysis (CV < 10% for all benchmarks)
- Performance interpretation (why 50x, why 100x, cache impact)

## Files
- **Modify**: `PERFORMANCE.md` (complete rewrite with architecture.md template)

## Dependencies
- speedup-validation-scripts (provides: validation script output)
- profiling-infrastructure (provides: --profile output data)
- cache-performance-benchmark (provides: cache hit/miss metrics)
- bug-fixes-verification (provides: stable baseline measurements)

## Provides
- Updated PERFORMANCE.md documentation
- Complete performance baseline table with all modes
- Stage-by-stage profiling analysis with percentages
- Statistical confidence metrics and variance analysis

## Acceptance Criteria
- [ ] AC6.6: Baseline table shows all 5 modes with mean latency and 95% CI
- [ ] AC6.6: Speedup calculations include vs CPython comparison (50x, 100x, 380x)
- [ ] AC6.6: Variance analysis section explains CV < 10% for benchmark stability
- [ ] AC5.5: Stage breakdown table integrates profiling data with time/percent columns
- [ ] Document includes reproducibility section with exact commands
- [ ] All numerical values match actual benchmark outputs from prior issues

## Testing Strategy

### Test Files
- `tests/test_performance_documentation.rs`: Validates PERFORMANCE.md structure and content

### Test Categories
- **Structure validation**: Parse PERFORMANCE.md and verify presence of 10 required sections (Executive Summary, Baseline Measurements, Stage Breakdown, Variance Analysis, Performance Interpretation, Bottleneck Analysis, System Requirements, Future Optimization, Reproducibility, Conclusion)
- **Data validation**: Extract numerical values from tables and verify they match expected ranges (binary 300-450μs, daemon 150-250μs, cached 40-70μs, CPython ~19ms)
- **Completeness checks**: Verify baseline table has 5 rows, stage breakdown has 5 stages summing to 100%, variance section mentions CV < 10%

### Run Command
`cargo test test_performance_documentation --release`
