Table of Contents

Before

bundle install --redownload
# 115.20s user 31.70s system 183% cpu 1:20.08 total

After

MAKE="make --jobs 8" bundle install --redownload
# 142.61s user 33.69s system 438% cpu 40.228 total

With a simple tweak, we halved the time needed to install the gems, which is very helpful for CI!

Why does this work

The MAKE environment variable must be passed in for the --jobs argument to work because it allows parallelization across CPU cores during the bundle install process.

The rake-compiler library, commonly used by native extensions, leverages make with the --jobs option to achieve true parallelism.

By setting the MAKE environment variable, you can significantly improve bundle install performance, especially if your Gemfile contains numerous native extensions and you’re using MRI with multiple CPU cores available.

Full explanation from this original blogpost I referenced - One Weird Trick That Will Speed Up Your Bundle Install