Progress/Spinner not working correctly when React render heavy page

[HRK44]

• This is a v1.x issue (v0.x is no longer maintained).
• I have searched the issues of this repository and believe that this is not a duplicate.

Expected Behavior

The progress should show correctly (spinning, loading, etc...).

Current Behavior

The progress component is not spinning/loading and stays frozen or is very thin (does not render well) when it's a circularprogress.

This is what a circularprogress looks like (size 50) :

Steps to Reproduce (for bugs)

1. Create a react page that takes some time to render (due to lof of components)
2. Set initial state in the constructor this.state.rendering = true
3. Set state in componentDidMount or in componentDidUpdate to this.state.rendering = false
4. Display conditionally the progress in the render() function base on this.state.rendering

Context

Your Environment

Tech	Version
Material-UI	v1.2.1
React	16.4
browser	Chrome Version 67.0.3396.99 (Official Build) (64-bit)

[oliviertassinari]

I'm closing as a duplicate of #10327

[HRK44]

Since this is a limitation, maybe we can add some notes in the doc to notify people?

[oliviertassinari]

@HRK44 Yes, we could! Do you want to work on it? :)

[HRK44]

On a side note, there is no api folder under docs/src/pages/, is it normal?