Define "slow". You shouldn't have to cache every page on your website just to get decent performance. Sounds like something else is wrong.
If your site is in any way dynamic, you won't be able to cache much anyway
If your site is in any way dynamic, you won't be able to cache much anyway
Many of these page renders require calls out to third-party APIs, which is responsible for some of the slowness. There are definitely optimizations that can be performed (e.g. caching the results of the backend APIs). But it's easier for less experienced developers to just cache the whole page with a reasonable TTL.
Also agreed that you won't be able to cache much (or as much) if the user is logged in. Logged in pages matter less for SEO, so we haven't focused too much on it.