Test SSSE3 percent encode cutoff

[thisalihassan]

Fork-only CodSpeed experiment for \n\nThis keeps the SSSE3 percent-encode path for longer inputs, but uses the scalar path for short inputs to avoid LUT setup overhead in short percent_encode benchmarks.

[codspeed-hq]

Merging this PR will improve performance by 12.84%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 1 improved benchmark
❌ 1 regressed benchmark
✅ 30 untouched benchmarks

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
❌	DecodeDense	6.7 µs	7.5 µs	-11.04%
⚡	url_search_params_AdaURL	196.1 µs	137 µs	+43.13%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing codspeed-percent-encode-ssse3-cutoff (370f532) with main (08cd431)}