Bug: Persistent Re-render Issue Despite Optimizations (React 18, Next.js, Hooks, Context)

[azorlu80]

Bug Report: Excessive Re-renders in Component Despite Multiple Optimizations

Description

A specific component in our Next.js application exhibits a high number of re-renders (approx. 8-10) even after all asynchronous data fetching (from APIs and Context) is complete and related loading states are false. This occurs despite applying various standard React optimization techniques, including memoizing context providers, functions, and derived state.

Steps to Reproduce

Unfortunately, isolating this issue into a minimal reproducible example has proven difficult due to the component's reliance on multiple contexts and asynchronous operations within our specific application structure. However, the core setup involves:

1. A dynamic route page component (e.g., /app/items/[itemId]/details/[detailId]).
2. The component uses useEffect to fetch data from two separate API endpoints based on route parameters (itemId, detailId) upon mount and when parameters change.
3. The component consumes data from two separate contexts (AuthContext, FeatureFlagContext) using useContext.
4. The component manages multiple states using useState for the fetched data, loading status, and error status for both API calls.
5. Data fetching functions are wrapped in useCallback.
6. Context providers for AuthContext and FeatureFlagContext have their value prop memoized using useMemo.
7. Derived state values (e.g., isPageLoading) are memoized using useMemo.
8. All major functions within the component are memoized using useCallback.
9. An attempt was made to consolidate multiple loading/error states into a single state object, which did not resolve the issue and potentially increased renders.
10. React Strict Mode is confirmed to be disabled.

Expected Behavior

After the initial loading phase and subsequent state updates settle (i.e., all loading states are false, data is populated), the component should render only once or twice more at most, ideally stabilizing without further renders until user interaction or prop changes occur.

Actual Behavior

Console logs show the component rendering approximately 8-10 times after all loading states (bolumLoading, previewsLoading, limitLoading) are false. This suggests that the sequence or batching of state updates within the asynchronous data fetching functions (fetchItemData, fetchDetailData) might be triggering an unexpected cascade of renders, even though the final state values are stable. The number of renders sometimes appeared to increase after applying useCallback to more functions or attempting state collocation.

Environment

• React: ^18
• Next.js: ^15.3.1
• Node.js: [22.14.0]
• OS: Linux (Pop!_OS 22.04 LTS)
• Browser: [1.77.97 Chromium: 135.0.7049.84 ]

Additional Context

We have applied standard optimization techniques (useMemo for contexts/derived state, useCallback for functions) as documented. The persistence of these extra renders after stabilization is unexpected and difficult to debug further without deeper insight into React's internal scheduling or potential interactions between multiple asynchronous state updates within useEffect.

[alapollon]

Hi there!, I've read your issue here. And however challenging I am wondering. if you would be interested in performing. A mock and spies test of your web bundle. To upload or email the results anywhere for diagnostics. It will be useful to help sort out the dependency

[cgx-system]

A useEffect with only one dependency and a simple console.log can help you check if any prop or state changes multiple times.
If not a prop or state, then you can do the same in the parent component, and so on until you find which one in the tree is re-rendering.
Can you share your code to help understand where the issue comes from ?