Ofri Peretz

Posted on Jan 2 • Edited on Jan 11

eslint-plugin-import vs eslint-plugin-import-next: Up to 100x Faster

#eslint #javascript #performance #benchmark

Up to 100x faster on circular dependency detection. Reproducible benchmarks. Full methodology.

🔄 Drop-in replacement — 100% compatible with all eslint-plugin-import rules, but faster, LLM-optimized error messages, and fewer false positives/negatives.

TL;DR

Benchmark	1K Files	5K Files	10K Files
Core Rules (9)	1.6x	3.3x	5.2x
Recommended Preset	1.4x	3.0x	5.5x
no-cycle Only	25.7x	54.9x	~100x*

*10K projection based on O(n²) scaling pattern observed at 1K→5K. We stopped at 5K because eslint-plugin-import would take 10+ minutes.

Why eslint-plugin-import is Slow

The original eslint-plugin-import uses an O(n²) module resolution algorithm:

For each file, parse all imports
For each import, resolve the full module path
For no-cycle, traverse the entire dependency graph for every file

This creates quadratic complexity. On 5,000 files with interconnected imports, the no-cycle rule alone takes 148 seconds.

How eslint-plugin-import-next Fixes This

We rewrote the core algorithms:

Cached module resolution — resolve each path once, cache permanently
Incremental graph building — build the dependency graph incrementally, not per-file
Cycle detection with Tarjan's algorithm — O(n) instead of O(n²)

Result: 2.71 seconds for the same 5,000 files.

Benchmark 1: Core Rules (9 rules)

Both plugins configured with identical rules:

no-unresolved, named, namespace, default, export
no-named-as-default, no-named-as-default-member, no-duplicates, order

Files	eslint-plugin-import	eslint-plugin-import-next	Speedup
1,000	2.80s	1.78s	1.6x
5,000	19.04s	5.76s	3.3x
10,000	58.67s	11.26s	5.2x

Takeaway: Even with basic rules, the performance gap grows with codebase size.

Benchmark 2: Recommended Preset

Using the full recommended configuration from each plugin.

Files	eslint-plugin-import	eslint-plugin-import-next	Speedup
1,000	2.42s	1.78s	1.4x
5,000	18.43s	6.07s	3.0x
10,000	57.74s	10.57s	5.5x

Takeaway: Recommended presets show similar scaling — 5.5x faster at 10K files.

Benchmark 3: no-cycle Rule Only

This is where the difference is massive. The no-cycle rule detects circular dependencies.

Files	eslint-plugin-import	eslint-plugin-import-next	Speedup
1,000	27.03s	1.05s	25.7x
5,000	148.59s	2.71s	54.9x
10,000	~600s (projected)*	~5s (projected)	~100x

*10K Projection Note: Based on the O(n²) scaling observed from 1K→5K (27s→148s = 5.5x increase for 5x files), we project eslint-plugin-import would take ~10 minutes at 10K files. We didn't run this because waiting 10+ minutes per iteration is impractical. eslint-plugin-import-next scales linearly (O(n)), so ~5s is expected.

Takeaway: If you use no-cycle (and you should), the speedup is 25-100x depending on codebase size.

┌────────────────────────────────────────────────────────────────┐
│ no-cycle Rule: 5,000 files                                     │
├────────────────────────────────────────────────────────────────┤
│ eslint-plugin-import:      148.59s ████████████████████████████│
│ eslint-plugin-import-next:   2.71s █                           │
└────────────────────────────────────────────────────────────────┘

Why no-cycle is Critical

Circular dependencies cause:

Build failures with tree-shaking
Runtime bugs with undefined imports
Memory leaks in bundlers
Test flakiness from initialization order

Most teams disable no-cycle because it's too slow. With eslint-plugin-import-next, you can finally enable it.

Methodology

Apple-to-apple comparison — full source code

Spec	Details
Codebase sizes	1,000 / 5,000 / 10,000 JavaScript files
Iterations	3-5 runs per size, per plugin
Fixtures	Realistic JS files with named/default imports, barrel files, cross-file dependencies
Environment	Node v20.19.5, Apple Silicon M1 (arm64), ESLint v9.17.0
Cache	Cleared between each run

Run It Yourself

git clone https://github.com/ofri-peretz/eslint-benchmark-suite.git
cd eslint-benchmark-suite
npm install
npm run generate:import
npm run benchmark:import
npm run benchmark:import-recommended
npm run benchmark:import-no-cycle

Migration Takes 2 Minutes

# Remove old plugin
npm uninstall eslint-plugin-import

# Install new plugin
npm install --save-dev eslint-plugin-import-next

// eslint.config.js
import importNext from 'eslint-plugin-import-next';
export default [importNext.configs.recommended];

Resources

📦 npm: eslint-plugin-import-next
📊 Benchmark Suite
📖 Full Rule List

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