2.0.0 Source map build performance

Is this a bug report?

No

Environment

Environment: OS: macOS High Sierra 10.13.6 Node: 8.12.0 Yarn: 1.9.4 npm: 6.4.1 Watchman: 4.9.0 Xcode: Xcode 9.4.1 Build version 9F2000 Android Studio: 3.0 AI-171.4443003

Packages: (wanted => installed) react: ^16.5.2 => 16.5.2 react-dom: ^16.5.2 => 16.5.2 react-scripts: ^2.0.0 => 2.0.0

Steps to Reproduce

1. npx create-react-app test-app # must use react-script@2.0.0
2. yarn add britecharts-react
3. Render any graph in App.js
4. yarn build

Expected Behavior

yarn build runs in a reasonable time

Actual Behavior

Build time jumps to 90 seconds, from 15 seconds

Reproducible Demo

Example Project

react-scripts@2.0.0 14.03s. (without britecharts)
react-scripts@2.0.0 89.04s (with britecharts)

react-scripts@1.1.5: 28.73s. (with britecharts)
react-scripts@1.1.5 : 6.93s. (without britecharts)

[cliedeman]

Sorry about that… I created a more robust setup script with docker and got exactly the same times across the board. I have no idea where I got those bundles sizes from and can’t reproduce them now.

I have removed that section from the issue to focus on the build time change

[cliedeman]

Updated the example project and split into 4 scenarios and added a single script so its easier to run.

Env	Cold (seconds)	Warm (seconds)
CRA 1.1.5 with britecharts	28.14	27.32
CRA 1.1.5 without britecharts	7.67	6.87
CRA 2.0.5 with britecharts	122.26	16.63
CRA 2.0.5 without britecharts	9.71	6.79