How do I keep marketing pages static while personalizing only a few routes?

Most of our site is static marketing content and I want it to stay fully static. Only a handful of routes actually need personalized slots, things like the logged-in dashboard landing and a couple of campaign pages.

I learned that fetchContent turns a route dynamic. What I want is a clear architectural rule so that only the routes that personalize pay that cost and the marketing pages keep rendering statically. How do people structure the app for this?