pyperformance doesn't show significant performance degration.  (using commit 5d8d3d1)

$ ./python -m perf compare_to -G --min-speed=2 default.json patched.json
Slower (5):
- pickle_list: 9.40 us +- 0.98 us -> 9.96 us +- 1.20 us: 1.06x slower (+6%)
- pickle_dict: 63.1 us +- 0.6 us -> 65.6 us +- 5.2 us: 1.04x slower (+4%)
- regex_effbot: 5.39 ms +- 0.09 ms -> 5.60 ms +- 0.35 ms: 1.04x slower (+4%)
- genshi_xml: 188 ms +- 2 ms -> 193 ms +- 3 ms: 1.03x slower (+3%)
- pickle: 22.4 us +- 0.2 us -> 22.9 us +- 0.3 us: 1.02x slower (+2%)

Faster (5):
- mako: 38.8 ms +- 0.2 ms -> 37.6 ms +- 0.2 ms: 1.03x faster (-3%)
- regex_v8: 44.3 ms +- 0.7 ms -> 43.1 ms +- 0.4 ms: 1.03x faster (-3%)
- scimark_monte_carlo: 254 ms +- 10 ms -> 248 ms +- 6 ms: 1.03x faster (-3%)
- scimark_fft: 740 ms +- 20 ms -> 721 ms +- 14 ms: 1.03x faster (-2%)
- regex_dna: 289 ms +- 5 ms -> 282 ms +- 9 ms: 1.02x faster (-2%)

Benchmark hidden because not significant (50)...