I wonder what website build performance will be like when he gets to 4,000 posts. Slow build times are why I have ruled out converting my website to Jekyll or Hugo. I've got over 4,000 active posts (and many with images) on my 14-year-old website. I create about one to three new posts per day. I can't imagine writing a post, waiting several minutes for the website to build, and then copying the files over to a server each and every time.
He made a lot of customizations to make things work faster. If he changes themes at some point In the future, he’ll need to redo the customizations.
I think the challenge for static site generators is that they were designed to be used for sites that don’t change often; e.g. corporate web sites. In other words, ststaic content. But now we have people, trying to shoehorn it for use with sites that update more often; e.g. blogs. Hence, the need to hack together work arounds. It’s klugely.
Best to use a system designed for dynamic web sites that have frequently updated content: e.g blogs. Ghost, WordPress, etc. do that well.