I also rewrote my blog's static site generator to a bespoke one (in Dart in my case), largely for performance reasons. Prior, I was using Jekyll and Pygments. Jekyll and Pygments are really slow. My new site generator is literally 100x faster, and I did, like, zero real optimization work. In fact, it can rebuild my entire blog and every post from scratch faster than Jekyll's watch mode (with caching set up properly) could rebuild a single page.