Let's face it, Magento 2 is slow. And it does not make sense that given how easy it is for the full page cache to be invalidated (add 1 product, change 1 thing in a CMS block etc.) that there isn't a way to clear just parts of the cache that are invalidated.
You clear the full page cache, and the generated cache of the store in its entirety is gone. This cache would have taken a good amount of time and resources to generate.
Optimisation, Varnish, Nginx tuning etc. is 1 aspect of it, but that's an external method. Internally I think the caching could work a lot better.
So what is the feasibility of building some smarts into the Magento 2 FPC so that it can selectively clear the generated cache on a per page basis?