If I used a SPA framework on these projects they would take me 100x longer to build a MVP with. If the project is viable and gets traction, then you could consider rewriting with a SPA like React or something.

It's incredibly fast, I still may try using https://github.com/marko-js/marko on v2 though since it seems to be much faster. Haven't really tried their plugin/system yet. I came from using Jade for like five years straight and when performance time came around with it, it hurt. Nunjucks is really nice!