speed up webpacker:compile in CircleCI — delete node_modules

TL:DR delete nodeModules from your environment.loaders in webpack/test.js

// webpack/test.js

process.env.NODE_ENV = process.env.NODE_ENV || 'development'

const environment = require('./environment')

environment.loaders.delete('nodeModules')

module.exports = environment.toWebpackConfig()

On our quest to get < 5 minutes CircleCI times we had a nasty surprise when updating our node version.

After going from node version 12 -> 14 we discovered that we had to add a step bundle exec rake webpacker:compile CircleCI.

This came at a hefty price of 75 seconds!

Deleting nodeModules from within webpack/test.js saved us about 30 seconds so down to 45 seconds.

Before

webpacker:compile taking 1m15s

After

webpacker:compile taking 45s