docs: add benchmark summary to README

Reference the GenCode vs Claude Code performance comparison in
README with key metrics table and link to full benchmark doc.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: Meng Yan <myan@redhat.com>

Author: yanmxa

README.md

@@ -113,6 +113,22 @@ GOCACHE=/tmp/gocache go test ./internal/transcriptstore ./internal/app/session .
 For the complete transcript persistence, resume/fork, and interactive vs non-interactive verification checklist, see `docs/transcriptstore.md`.
 
 
+## 📊 Benchmark: GenCode vs Claude Code
+
+Compared with [Claude Code](https://claude.ai/code) v2.1.96 on Apple Silicon, same model (`claude-sonnet-4-20250514`):
+
+| Metric | GenCode | Claude Code | Advantage |
+|--------|---------|-------------|-----------|
+| Install size | 38 MB | 174 MB | **4.6x smaller** |
+| Startup time | ~0.02s | ~0.18s | **9x faster** |
+| Startup memory | ~33 MB | ~185 MB | **5.6x less** |
+| Simple task | ~5.2s / 39 MB | ~11.9s / 282 MB | **2.3x faster, 7.2x less memory** |
+| Tool-use task | ~3.6s / 40 MB | ~14.6s / 281 MB | **4.1x faster, 7.1x less memory** |
+
+Go's native compilation produces a single static binary with minimal runtime overhead, while Node.js carries V8/JIT/GC baseline costs. Claude Code also performs more startup work (hooks, LSP, plugin sync, memory, etc.).
+
+See full details: [docs/benchmark-gencode-vs-claudecode.md](docs/benchmark-gencode-vs-claudecode.md)
+
 ## 🔗 Related Projects
 
 - [Claude Code](https://claude.ai/code) — Anthropic's AI coding assistant