Rendering issue on new landing pages

Upon initial load (uncached) of any one of my new landing pages, I see (for a split second) a colored background, a huge logo (my company’s logo) and unstyled page elements. I’m on Chrome/MacOS.

Here’s an example:

All my other (new) landing pages are showing this split-second loading issue. My hunch is that the CSS code is not ideally optimized and is simply taking a while to render. But wanted to post this to see if others are experiencing this and if IS staff may have any insights/ideas.