Recently, I started exploring React performance optimization, and one of the first concepts I studied was React.memo. Instead of creating a new project just for practice, I decided to revisit one of my old projects called Atomic Blog and improve its codebase.
Working on an existing project helped me understand performance optimization in a much more practical way.
This time, I focused on understanding how React rendering works and how unnecessary re-renders can affect application performance.
What is React.memo?
React.memo is a performance optimization technique that prevents a component from re-rendering if its props have not changed.
Normally, when a parent component re-renders, all of its child components re-render as well — even if their data did not change.
React.memo helps avoid that.
Instead of always re-rendering, React compares the previous props with the new props.
If nothing changes, React skips the render.
That means:
- Less rendering work
- Better performance
- Faster UI updates
Where I Used React.memo
I used React.memo on a component that renders a large list of posts.
Instead of re-rendering thousands of items every time the parent component updated, React.memo ensured the component only re-rendered when necessary.
The idea looked like this:
const Archive = memo(function Archive({ show }) {
// Component logic
});
This small change can make a big difference in applications that render large datasets.
Understanding React Rendering
One important thing I understood during this practice is that:
React components can re-render more often than we expect.
Even small state changes in parent components can trigger child component renders.
Without optimization, this can slow down the application.
This made me realize that performance optimization is not just about writing code — it is about understanding how React updates the UI.
Using React DevTools Profiler
Another important part of this learning was using the React DevTools Profiler.
The Profiler helped me visualize how components render.
I could clearly see:
- Which components re-rendered
- How often they rendered
- Which renders were unnecessary
- Which components were expensive
This made performance optimization much easier to understand because I could actually see what React was doing behind the scenes.
Why Revisiting Old Projects Helps
Instead of always building new projects, improving old codebases helped me learn more deeply.
By revisiting the Atomic Blog project, I was able to:
- Understand real rendering behavior
- Practice performance optimization
- Improve existing architecture
- Learn debugging tools like Profiler
This approach feels closer to real-world development where codebases evolve over time.
Key Takeaways
- React.memo prevents unnecessary re-renders
- Rendering behavior is important to understand
- Large components benefit most from optimization
- React DevTools Profiler is extremely useful
- Improving old projects builds deeper understanding
Next Steps
Next, I plan to continue learning React Performance Optimization, including:
- useMemo
- useCallback
- Rendering optimization patterns
- Performance measurement techniques
After understanding these concepts deeply, I will apply them inside my main projects(lunara).
If you are learning React, I highly recommend revisiting old projects and optimizing them. It teaches much more than small isolated examples.
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