perf(hooks): avoid redundant allocations and writes in SCU and diffed (#5115)

(cherry picked from commit 6aced21)

Author: JoviDeCroock

hooks/src/index.js

@@ -86,8 +86,8 @@ options.diffed = vnode => {
 		c.__hooks._list.some(hookItem => {
 			if (hookItem._pendingArgs) {
 				hookItem._args = hookItem._pendingArgs;
+				hookItem._pendingArgs = undefined;
 			}
-			hookItem._pendingArgs = undefined;
 		});
 	}
 	previousComponent = currentComponent = null;
@@ -240,16 +240,14 @@ export function useReducer(reducer, initialState, init) {
 			function updateHookState(p, s, c) {
 				if (!hookState._component.__hooks) return true;
 
-				const hooksList = hookState._component.__hooks._list;
 				// We check whether we have components with a nextValue set that
 				// have values that aren't equal to one another this pushes
 				// us to update further down the tree
-				let shouldUpdate =
-					hookState._component.props !== p ||
-					hooksList.every(x => !x._nextValue);
-
-				hooksList.some(hookItem => {
+				let updatedHook = false;
+				let shouldUpdate = hookState._component.props !== p;
+				hookState._component.__hooks._list.some(hookItem => {
 					if (hookItem._nextValue) {
+						updatedHook = true;
 						const currentValue = hookItem._value[0];
 						hookItem._value = hookItem._nextValue;
 						hookItem._nextValue = undefined;
@@ -258,9 +256,12 @@ export function useReducer(reducer, initialState, init) {
 					}
 				});
 
-				return prevScu
-					? prevScu.call(this, p, s, c) || shouldUpdate
-					: shouldUpdate;
+				if (prevScu) {
+					const result = prevScu.call(this, p, s, c);
+					return updatedHook ? result || shouldUpdate : result;
+				}
+
+				return !updatedHook || shouldUpdate;
 			}
 
 			currentComponent.shouldComponentUpdate = updateHookState;