Reanimated Fast Context
Jack Herrington's Fast Context (fast-context-generic example), now with an additional version based on Reanimated's useSharedValue.
As of v0.1.0, calling the returned useFastContext hook of createFastContext/createReanimatedContext without an argument results in a default selector of (store) => store (in other words, "selects" the entire object you supplied to initialize createFastContext).
npm i or yarn add @scienceartmagic/rfc react-native-reanimated
Technically, Reanimated is only required if you want to use createReanimatedContext() (which uses Reanimated's useSharedValue() hook under the hood). The default export createFastContext() (not far from @jherr's original version), which uses React's useRef() hook under the hood, has no other external dependencies.