# React Performance Anti-Patterns: 5 Mistakes That Kill Your App's Speed!

Is your React app dragging its feet, but you can’t pinpoint the cause?

You might think you’re following the best practices, but some common development patterns are actually degrading your app’s performance behind the scenes.

In this article, we’ll uncover 5 sneaky anti-patterns that are silently killing your React app’s speed, and show you how to fix them for a faster, smoother user experience.

So let’s get started.

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## 1. Context Causing Mass Re-renders
    

**The Problem:** Adding everything in a single context.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1765379796364/7727c9ef-dfd8-4c65-b94c-3b5efbbbbff6.png align="center")

**The Solution:** Split contexts by concern.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1765379892275/aab3ae39-a7bb-45fd-a71d-f55b0a6622f6.png align="center")

 ## 2. Inline Object/Array Creation in Props
    

**The Problem:** Passing inline objects/arrays as props to a component.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1765386603113/66772436-f826-4e23-8ee9-64bb5fe2290c.png align="center")

**First Solution:** Define constants outside the component.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1765378662274/773d374d-14fc-47a5-ac66-9b1a390a9de3.png align="center")

**Second Solution:** Use useMemo for dynamic values.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1765378862836/ce99025b-b6ed-44a4-9695-a5ee1ed18dec.png align="center")

## 3. Rendering Everything in a Huge List

**The Problem:** Displaying the entire list at once.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1765386710910/4d587526-e914-4641-9b95-d8632302003e.png align="center")

**The Solution:** Use React Window/React Virtualized library.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1765379101894/7ac38d74-408b-4ea8-aa99-641d5c74ea1d.png align="center")

## 4. Not Memoizing Expensive Calculations

**The Problem:** Calculating values during rendering.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1765379408364/a676ad03-545d-4bac-a335-d06f10541bca.png align="center")

**The Solution:** Use the useMemo hook.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1765379511867/1882f7f8-9102-4fc9-847a-6d9c8665066c.png align="center")

## 5. Anonymous Functions in JSX

**The Problem:** Creating new functions on every render.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1765385903951/548cc750-74c4-4e04-be41-60860488dbf9.png align="center")

**The Solution:** Use event delegation.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1765386007704/c0e31a78-5980-4983-b245-dd9a5077d6a5.png align="center")

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