# Feedback: CPython Comparison Benchmark

## Status: FIX REQUIRED

**Tests**: ✅ All 126 tests passing
**Code Review**: ✅ Functionally approved
**Issue**: ❌ Missing required deliverable (AC1.4)

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## Critical Issue

### Create PERFORMANCE.md Documentation (AC1.4)

**Location**: Create new file `PERFORMANCE.md` in repository root

**Required Sections**:
1. **Methodology**: Document the comparison approach (identical Python code, statistical confidence method, benchmark setup)
2. **Results**: Populate with actual speedup metrics from `compare_cpython.sh` output (speedup ratio, confidence intervals, warm vs total execution times)
3. **Breakdown**: Include timing breakdown for both PyRust and CPython execution
4. **Comparison**: Show side-by-side comparison of results

**Action**:
- Capture output from `scripts/compare_cpython.sh` execution
- Extract the speedup ratio (~62,000x), confidence intervals (95%), and timing data
- Create PERFORMANCE.md with these four required sections
- Include example output from the benchmark comparison

**Why**: The PRD explicitly requires AC1.4 as a deliverable. This documentation enables users to understand the performance characteristics and serves as a baseline for tracking performance regression in future versions.

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## Non-Blocking Items (No Action Required)

These are suggestions for future improvement, not blockers:

1. **Readability**: Variable expansion in `scripts/compare_cpython.sh` lines 159, 165, 175-176 mixes shell and Python syntax — consider refactoring for clarity in a future PR
2. **Validation**: The `extract_timing()` function (lines 71-76) could validate that jq extraction returns valid numbers — low priority since Criterion's JSON format is stable

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## Summary

AC1.3 (speedup validation) is complete and tested. AC1.4 (PERFORMANCE.md documentation) is the only missing piece. Once the documentation file is created with the required sections populated from the comparison script output, this issue will be complete.
