# Benchmarking Go 1.27's New JSON API Against the Legacy Implementation

DevFeed: [Benchmarking Go 1.27's New JSON API Against the Legacy Implementation](<https://devfeed.tech/articles/the-new-go-json-api-twice-as-fast-or-1-5x-slower-29425.md>)

Original publisher: [Read original article](<https://lemire.me/blog/2026/08/29/the-new-go-json-api-twice-as-fast-or-1-5x-slower/>)

Author: Daniel Lemire

Published: 2026-08-29T18:33:33Z

Content type: opinion

Language: en

Sources: [Daniel Lemire](<https://devfeed.tech/sources/daniel-lemire.md>)

Topics: [Go Language](<https://devfeed.tech/topics/go-language.md>), [JSON](<https://devfeed.tech/topics/json.md>), [Programming](<https://devfeed.tech/topics/programming.md>)

Tags: [go](<https://devfeed.tech/tags/go.md>), [json](<https://devfeed.tech/tags/json.md>), [performance](<https://devfeed.tech/tags/performance.md>), [release](<https://devfeed.tech/tags/release.md>)

## AI overview

The article benchmarks Go 1.27's new JSON engine and APIs against the original implementation across several documents and operations. Results vary by workload: the new API generally improves unmarshalling and can substantially improve marshalling, but the legacy implementation remains faster for some structured data cases.

## Source excerpt

JSON is a standard format for data interchange. It is effectively a tiny subset of JavaScript made of objects and arrays. It looks as follows {"key":1, "text":[1.0,2.0]}. Many programming languages include a JSON library in their standard libraries: C#, Go, Java (soon), Python, JavaScript, etc. The Go implementation is convenient, but not especially fast. Go ... Continue reading The new Go JSON API: twice as fast, or 1.5x slower?