perf: faster pack/unpack (no breaking changes) - #35
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Reduce pack allocations with tagged-integer AST leaves, pre-sized containers, cached base36, static escape maps, and join-based structure emission. Add decode fast-path. Public API and packed output unchanged.
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Summary
Internal performance improvements to
pack/unpackwith no API or packed-format changes.Changes
{ type, index }objects (less GC on pack)Object.keys/ known lengths)join(avoids quadratic concat)Object.create(null)dictionariesBenchmark (same machine, before vs after)
Node v25 / win32 x64 / i5-1340P — full table in
benchmark/COMPARISON.md.Examples:
geojson-largepack: 177 → 294 ops/s (+66%), unpack: 457 → 478 ops/s (+5%)api-largepack: 153 → 270 ops/s (+77%)ecommerce-largepack: 102 → 220 ops/s (+116%)CPU stays ~100% of one core during the hot loop (CPU-bound); wall-clock CPU time per op drops with throughput. RSS stays in a similar band.
Related: benchmark harness in #34.
Test plan
npm test— 22/22 passing (byte-identical packed fixtures)