google – Lazy loading sections of website and SEO

I have an interactive WordPress website with multiple animations / images. I wanted to improve Google Insight's speed performance, while preserving SEO optimization for the site.

The proposed enhancement includes lazy loading of all sections.

The steps are as follows:
1) Display the homepage of the site with a minimum of semantic tags and barely styles. The content is hidden behind the overlay

The purpose of this point is to provide content for Google robots.

2) Use AJAX to load the main screen that replaces the minimal text.
3) Lazy load other sections on the scroll.

The points are meant to provide better loading times and a better user experience.

Is such a practice bad for SEO? I mean, does Google penalize him? The text content is not changed.