I use Jekyll for my company website [1] and managed to get a lot of speed optimisations simply by using a post-processing tool on the statically generated output.
For my product website, it reduced the overall size by 590MB or approximately 59% in size, along with changing the HTML/CSS to make the optimisations that this article notes.
The tool I use is Jampack and I'd highly recommend it: https://jampack.divriots.com
For my product website, it reduced the overall size by 590MB or approximately 59% in size, along with changing the HTML/CSS to make the optimisations that this article notes.
[1] https://www.magiclasso.co/