I think the work you are doing right can be a stepping stone for something great! The advantages of more traditional methods of creating CSS are ahead-of-time-compilation, splitting/bundling (combine common chunks to achieve low cache invalidation, low transfer size, and high cache hits with few files), and no waiting for the JS-engine to parse and convert your internal data structure. SPA-SSR is in general a lot more CPU-heavy than the more traditional approach of instantiating templates. We need to find ways of minimising the redundant calculations performed by the server to regain the performance we lost in the transition from templates to SPA-SSR. A source code transformation that extracts CSS and removes static JS is one such step. The SSR API is a good start but completely trashes cache + creates a large .html each time you reload. The .html returned can most often not be cached so we should strive to minimise its size. The problem of caching/minimising server load is not the easiest to solve but we should be long on our way if we can analyse/signal what parts are static and which are dynamic.