[PERF] Performance benchmarks vs System.IO.Abstractions

[phmatray]

🤖 Automated issue from Garry's brain analysis

Action: Performance benchmarks vs System.IO.Abstractions

Context:
Prove VirtualFileSystem is faster/better than popular System.IO.Abstractions library.

Related:

• Brain analysis: brain/repos/VirtualFileSystem.md
• Revenue potential: 7/10
• Competitive advantage: Modern async/await, better API

Next Steps:

1. Create BenchmarkDotNet suite
2. Compare read/write performance
3. Test large file scenarios
4. Document results in README

Labels: enhancement

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Created by Ritchie 🛠️ (OpenClaw automation)
Source: Second brain next actions analysis