Introduction

MUI components rely on React’s rendering cycle and CSS-in-JS styling solutions such as Emotion or JSS. When components are not optimized, unnecessary re-renders can occur due to prop changes, dynamic styling re-evaluations, or inefficient state management. This results in UI lag, slow page transitions, and poor overall performance. This article explores the causes, debugging techniques, and solutions to prevent excessive re-renders and improve Material-UI performance.

Common Causes of MUI Performance Degradation

1. Unnecessary Component Re-Renders

When a parent component updates, all child components re-render, even if their props have not changed.

Problematic Code

const ParentComponent = () => {
  const [count, setCount] = useState(0);

  return (
    <div>
      <button onClick={() => setCount(count + 1)}>Increment</button>
      <ChildComponent />
    </div>
  );
};

const ChildComponent = () => {
  console.log("ChildComponent rendered");
  return <Typography>Hello!</Typography>;
};

Solution: Use `React.memo` to Prevent Unnecessary Re-Renders

const ChildComponent = React.memo(() => {
  console.log("ChildComponent rendered");
  return <Typography>Hello!</Typography>;
});

2. Inefficient Inline Styles Causing Re-Renders

Using inline styles inside components triggers re-renders due to new object creation on each render.

Problematic Code

const MyComponent = () => {
  return <Button style={{ backgroundColor: "blue" }}>Click Me</Button>;
};

Solution: Use `useMemo` to Cache Style Objects

const MyComponent = () => {
  const buttonStyle = useMemo(() => ({ backgroundColor: "blue" }), []);
  return <Button style={buttonStyle}>Click Me</Button>;
};

3. Expensive Theme Computation

Using `useTheme` inside components can cause unnecessary theme re-computations and re-renders.

Solution: Move Theme Usage Higher in the Component Tree

const theme = useMemo(() => createTheme({ palette: { primary: { main: "#1976d2" } } }), []);
return (
  <ThemeProvider theme={theme}>
    <MyComponent />
  </ThemeProvider>
);

4. Over-Reliance on Dynamic Styling

Material-UI’s styling system regenerates styles when props change, leading to performance overhead.

Solution: Use Static Styles Instead of Dynamic Props

const useStyles = makeStyles(() => ({
  button: {
    backgroundColor: "blue",
  },
}));

5. Large Data Tables with Unoptimized Rendering

Rendering large tables with MUI `Table` components can be slow if all rows re-render on every state change.

Solution: Use `React.memo` and Virtualization

const MemoizedRow = React.memo(({ row }) => (
  <TableRow>
    <TableCell>{row.name}</TableCell>
  </TableRow>
));

Debugging MUI Performance Issues

1. Using React DevTools to Identify Unnecessary Re-Renders

1. Open React DevTools in Chrome.
2. Enable "Highlight updates when components render".
3. Observe unnecessary updates in the UI.

2. Measuring Component Render Time

console.time("Render Time");
<MyComponent />
console.timeEnd("Render Time");

3. Checking Re-Renders with `why-did-you-render`

import whyDidYouRender from "@welldone-software/why-did-you-render";
whyDidYouRender(React, { trackAllPureComponents: true });

4. Using the Profiler API to Detect Slow Components

import { Profiler } from "react";

<Profiler id="MyComponent" onRender={(id, phase, actualDuration) => {
  console.log(id, phase, actualDuration);
}}>
  <MyComponent />
</Profiler>

5. Monitoring State Changes

useEffect(() => {
  console.log("State changed", state);
}, [state]);

Preventative Measures

1. Memoize Functional Components

const MyComponent = React.memo(() => {...});

2. Cache Styles with `useMemo`

const styles = useMemo(() => ({ color: "blue" }), []);

3. Avoid Inline Functions in JSX

const handleClick = useCallback(() => {...}, []);

4. Use Virtualized Lists for Large Data

import { FixedSizeList as List } from "react-window";

5. Optimize Theme Computation

const theme = useMemo(() => createTheme({...}), []);

Conclusion

Performance degradation in Material-UI due to excessive re-renders and inefficient styling can slow down React applications. By memoizing components, caching styles, optimizing state updates, and using virtualization for large datasets, developers can improve MUI performance. Debugging tools like React DevTools, `why-did-you-render`, and the Profiler API help identify and resolve performance bottlenecks efficiently.

Frequently Asked Questions

1. Why is my Material-UI app slow?

Excessive re-renders, inline styles, and dynamic theme computations can cause performance issues.

2. How do I reduce re-renders in MUI components?

Use `React.memo`, `useMemo` for styles, and `useCallback` for functions.

3. How can I optimize large tables in MUI?

Use virtualization libraries like `react-window` or `React.memo` for rows.

4. Does `useTheme` impact performance?

Yes, excessive `useTheme` calls can cause theme recomputations and unnecessary re-renders.

5. How do I debug performance issues in MUI?

Use React DevTools, the Profiler API, and `why-did-you-render` to track unnecessary renders.