Performance: plugin adds 150-200ms to ESLint startup time because of ramda

[victor-homyakov]

ESLint is frequently used in pre-commit hooks. Just adding eslint-mocha-plugin makes linting and commiting noticeably slower even when there is nothing to lint.

Steps to reproduce

1. Create clean new folder
2. Install npm i eslint-mocha-plugin
3. Create script and execute it in Node.js:

const label = 'require plugin';
console.time(label);
const plugin = require('eslint-plugin-mocha');
console.timeEnd(label);

On MacBook Pro with 2,7 GHz Intel Core i5 it gives me 150-200 ms. In other words, just adding this plugin slows startup of ESLint by 150-200ms.

The problem is in require('ramda') - loading ramda module requires that much time. It's OK for long-running applications, but for command-line utilities it is inappropriately slow.

Is it possible to speedup startup time of plugin by rewriting the code without ramda?

[lo1tuma]

What makes you think this is caused by ramda? On my machine it takes ~170ms for requiring eslint-plugin-mocha, but only ~70ms for requiring ramda.

[lo1tuma]

I’ve made some optimizations in #214. I think it is not related to the CPU speed, but rather to I/O speed. The ramda entrypoint file does ~250 require calls.

[victor-homyakov]

What makes you think this is caused by ramda?

1. I profiled requiring index.js - most of the time was spent on require('./lib/rules/no-exclusive-tests')
2. Most of the time in no-exclusive-tests.js was spent on const astUtils = require('../util/ast');
3. Profiling ast utils pointed me to line const R = require('ramda');