Next.js 15 simplifies caching with the experimental `Dynamic IO` API. Previously, caching was complex and inconsistent. `use cache` and `cache.tag` directives now offer granular control over caching behavior for individual components, functions, and routes, allowing for dynamic data fetching alongside cached content using suspense. This improves performance and developer experience, although the system remains experimental. by default, everything is cached in XJS, like a server component that defines a web page, and also any calls you make to the fetch function would be cached by default to try to optimize performance by preventing the server from doing extra work and rendering the same page over and over again In next 14 The problem is that in some cases, you might have multiple data fetching operations to render a page, you might want some of them to be cashed, but you might want others to be revalidated on every request and opting out of the cash could be pretty annoying.