Pre-commit Hooks 15× Faster (Biome vs ESLint case study)

What is this case study about?

This case study documents how the fireup.pro engineering team reduced pre-commit hook execution time from ~27 seconds to ~1.8 seconds in a large TypeScript monorepo by replacing most of the ESLint + Prettier pipeline with Biome a Rust-based formatter and linter. The result: 92.6% faster pre-commit hooks with no loss in code quality and no breaking changes to existing workflows.

The Problem: ESLint + Prettier Bottleneck

The starting setup was standard for a modern JavaScript/TypeScript project:

• ESLint for linting
• Prettier for formatting
• lint-staged for pre-commit automation

In a large monorepo, this stack became a bottleneck. Pre-commit hooks were taking 24–30 seconds per commit, slowing down developer workflow, reducing commit frequency, and generating friction across the team. This is a common problem in scaling frontend and fullstack teams.

What is Biome?

Biome is an open-source toolchain for JavaScript and TypeScript that combines a formatter and a linter in a single binary written in Rust. It has zero npm dependencies, runs significantly faster than ESLint + Prettier, and uses a unified configuration file. Biome is designed as a drop-in replacement for the ESLint + Prettier combination in most projects, with coverage for TypeScript, React, JSX, JSON, and CSS.

The Solution: Biome + Minimal ESLint (Hybrid Approach)

Rather than doing a full replacement, the team adopted a hybrid architecture: Biome handles 90% of formatting and linting tasks, while a minimal ESLint configuration is retained for rules Biome does not yet support.

New pre-commit pipeline

1. Biome (primary engine)

• Formatting: quotes, semicolons, indentation
• Linting: TypeScript, React, accessibility, security
• Import sorting
• JSON formatting

2. Minimal ESLint (edge cases only)

• JSDoc validation, critical for large codebases with over 1.1M JSDoc comments
• Promise rules (param-names)
• Custom rules not yet supported by Biome

3. Prettier (limited scope)

• Tailwind CSS class sorting in selected apps only

Performance Results

The benchmark result for a representative commit: 27.2s → 1.8s, a 92.6% reduction in execution time.

Code Quality: 92% Rule Alignment

Maintaining code quality was a hard requirement. The hybrid setup preserved 92% of the previous ESLint ruleset, including:

• TypeScript strict rules
• React and Hooks best practices
• Accessibility checks
• Security linting
• Unused variable detection
• Import organization
• JSDoc validation (1.1M+ comments in the codebase)
• Promise handling rules

No critical regressions were introduced.

Zero breaking changes

The migration was fully backward compatible:

• Existing commands still work (yarn lint, yarn lint:fix)
• No changes required from developers
• ESLint still available where needed
• CI/CD pipelines unchanged

Business impact

Faster pre-commit hooks directly affect engineering throughput. With ~24 seconds saved per commit, multiplied across dozens of commits per day and a multi-person team, the cumulative time saved is significant. The practical outcomes:

• Smoother development flow from faster commit cycles
• More frequent commits, leading to smaller and safer changes
• Faster feedback loop, catching issues before they reach CI/CD
• Reduced developer frustration from waiting on tooling

When to use biome

Biome is a strong fit when:

• You have a large monorepo with slow lint-staged pipelines
• Your ESLint configuration is complex and slow to initialize
• You have 5+ developers committing frequently
• Pre-commit or CI/CD performance is a bottleneck

When to stay with ESLint

ESLint remains the better choice when:

• You rely heavily on custom or third-party ESLint plugins with no Biome equivalent
• You have strict enterprise linting policies tied to specific ESLint rules
• Your ruleset depends on features Biome does not yet support

Biome vs ESLint + Prettier: Summary

If your team is dealing with slow CI/CD pipelines, monorepo performance issues, or frontend scalability challenges, see how fireup.pro’s frontend development services can help.