Your Linter Needs to Be as Fast as Your AI

ESLint was slowing down the development loop for the reporter, making the save-and-check cycle feel sluggish. Claude Code or Codex could provide a complete patch, but ESLint then made the developer wait to determine if the patch was usable. Biome, on the other hand, made this process feel immediate. While ESLint wasn't designed for a workflow where an AI commits 300 lines at once, Biome was built for speed and efficiency.

Biome is a linter and formatter written in Rust, with its own parser and no dependency on the TypeScript compiler. In contrast to ESLint, which parses files with one tool and then formats them again with another, Biome parses the files once and runs both passes on the same Abstract Syntax Tree (AST). This reduces formatting time by up to 25 times and linting time by up to 15 times when compared to ESLint, according to Biome's own benchmarks.

Biome's config is simpler, with a single biome.json file, and it runs all tasks (lint, format, and import sorting) in one pass. To use Biome, developers need to install the package, generate a biome.json file, and update their package.json scripts to include lint, format, and check commands. Biome also offers a VS Code extension as the default formatter.

While Biome has a smaller rule surface than ESLint, and doesn't support type-aware rules, it runs significantly faster due to its single-pass parsing and Rust-based rules. For the reporter, the speed difference was immediately noticeable in the save-on-format loop, making fast feedback possible. The reporter gave up a handful of type-aware rules they were barely reading the output of, but gained a linter they could leave on and trust.