Inability to prioritise hydration & react yields too willingly

# Summary React does not provide an API to set the priority on a component or suspense boundary for hydration. This means you cannot optimise your application to hydrate part of the app you know users will want to interact with first. Or in my case a part of the application I need to start rendering client side asap to replace a SSR skeleton with the correct personalised content that can only be rendered client side. The issue is compounded by the way React 18 yields the main thread during hydration to other higher priority events, which while a great idea in theory to improve FID and INP, in practice means 3rd party loaded (gtm) scripts delay the initial hydrating. It would be great if this logic could differentiate between user interactions and scripts added to the call stack? Detailed here https://github.com/reactwg/react-18/discussions/38#discussioncomment-837161 My real-world use case is an ecommerce application where marketing teams are loading via gtm vast amounts of 3rd party scripts, think tiktok, instagram, bing, and masses of gtm containers. While the ideal solution would be to either trim these down or move them to the worker threads via something like partytown (https://partytown.builder.io/), neither is realistic. As such we need a way to optimise around them. We can see, on slower windows machines and older mobiles, initial hydration of components take more than 5-8 seconds to start. This provides a negative experience to customers where skeletons are visible, and a worse UX than the legacy MVC sites. ##Work arounds As detailed here there are potential workarounds that already exist https://github.com/reactwg/react-18/discussions/130 Firstly the `unstable_scheduleHydration` API, however this has since been moved to the hydrateRoot function and is no longer accessible in Next.js (I believe?) (https://github.com/facebook/react/pull/22455/files) The second, and this is where you have to forgive me, is to creatively interpret the following…