Go 1.27 New JSON API Benchmark: Twice as Fast or 1.5x Slower?

lemire · x · 2026-08-30

This article benchmarks the new JSON package (encoding//v2) in Go 1.27. While the new and legacy APIs look similar, differences in Unicode validation and case sensitivity mean the new engine is not a drop-in replacement. The legacy API can also run on top of the new engine. Benchmarks show significant speedups in some scenarios, but potential slowdowns under specific conditions.

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