React Application Optimization Best Practices

It doesn’t take long in React app development to finally start reaching towards optimization of the application due to some strange error or a re-render, and whether you are just starting out in your career or you are a React expert – its always a good idea to have a good set of tools and protocols to follow when you need to optimize your application.

Some of the most common issues with React are re-renders, state issues and compilation times. Where the recent trend, stemming from better Infrastructure tools and cheap prices has caused many to forget about issues in their web applications since most of the issues could be resolved by increasing parameters of infrastructure such as memory, processors and disc space.

An engineer capable of producing optimized web applications will be able to save his organization thousands of dollars in Infrastructure costs – should he include optimization cycles in his development.

About Optimization Cycles

“I see what this article is going towards.. but my clients keep requesting other features!” is the much repeated Mantra of small-medium application owners. Whether you are working in a corporation and been tasked with optimizing a certain component or have your own application – understand this, both in business and software development it is absolutely necessary to step back and address the whole issue for the sake of further, proper development. Consider the fact that it is often the case for business owners to incur a one month sales penalty for the sake of training a new employee for example, and in turn, increase revenue overall.

Sure, the optimization tasks could always be postponed, but including them – on a periodic timeframe, once in a development cycle or in two development cycles, will keep the application clean and easy to maintain.

Understanding the issue

To understand the problem, we first must classify the issue, ask yourself..

Do I understand what is React Component Lifecycle?
Is this problem, potentially related to the React Component Lifecycle?
Are there any unused imports or packages in my application?
Does my issue affect compilation times?

We must understand if the issue is related to ..

Inefficient rendering of application components
State passing or updates
Bundle size / Compilation
Inefficient code

Some of the most valuable tools to start debugging would include things like..

Webpack Analyzer – If your application includes web pack analyzer, you can generate a heat map that shows you which components are the heaviest and which are not. If you are not such whether you have it or not, your project will usually include webpack.config.js file , if you indeed are using web pack.
Sourcemap analyzer – projects without webpack, such as Vite framework can utilize source map analyzer for the same purpose.
React DevTools – This wonderful extension is so useful in identifying problematic parts of our application. With the use of profiler we can record the rendering of the applications and see which ones took the most time to render and how many times did they appeared. A wonderful explanation on the topic could be found here, available on Chrome and Firefox.
Redux DevTools – If your application uses Redux for its state management, this tool can be helpful in tracking changes in state as they either occur or fail. Available as an extension here.
Preact & Preact Signals – Stuck in Redux Hell? Get out of it with this wonderful package that allows various, built in React features but without the un-necessary overhead that comes with it. And while Preact Signals requires its own article, it is a wonderful solution to track state across your application in a granular way! (Which is just a fancy way to say that it will not re-render all the parent components when you call or update it). It’s a neat and clean solution that doesn’t require you to write actions-reducers and is very maintainable, it’s all you’ve ever wanted from Redux and more. Check it out here.
Normalizr – Working with large scale API calls? Reduce your repetitive code and solve data duplication by normalizing your responses according to your wanted Schemas! This solution is great for medium to large scale applications and allows clean and maintainable code. While this package is no longer maintained, it has remained a great stable solutions for many applications. Read more about this wonderful package here.

Let us define a protocol we could follow, in order to understand where are the problematic areas and ensure we optimize those as best to our abilities in 10 most efficient steps.

Step 1: Establish a Baseline

Measure Initial Performance: Use tools like Lighthouse, React Profiler, and Redux DevTools to establish a performance baseline. Identify key metrics like time to interactive (TTI), bundle size, and initial state size.
Identify Pain Points: Gather user feedback and monitor analytics to identify specific areas where users experience delays or performance issues.

Step 2: Analyze the React Component Lifecycle

Review Component Rendering: Use the React DevTools Profiler to analyze which components are rendering too frequently or taking too long to render.
Check for Unnecessary Re-Renders: Identify components that re-render unnecessarily and consider using React.memo, useMemo, or useCallback to optimize rendering.

Quick Reminder

React.memo: Prevents re-renders of a component unless its props change.
useMemo: Memoizes the result of an expensive calculation, so it’s only recalculated when dependencies change.
useCallback: Memoizes a function, so it isn’t redefined unless its dependencies change.

Step 3: Audit the Redux State Management

Inspect Redux Actions and State Changes: Use Redux DevTools to monitor state changes and action dispatches. Identify any unnecessary or redundant actions that might be causing excessive state updates.
Analyze State Shape: Review the structure of your Redux state. Ensure it’s normalized and optimized for quick lookups and updates.
Use Signals instead of React Hooks/Redux – To make sure you avoid problems in the future with State management, a new way has been developed to make sure that complex component trees can now safely access their states. Read more about here

Step 4: Optimize State Management Logic

Refactor Reducers: Simplify complex reducers and ensure they only update the necessary parts of the state. Use tools like immer to manage immutable state updates more efficiently.
Modularize State: Consider breaking down large pieces of state into smaller, more manageable slices to reduce the complexity and improve maintainability. While rarely we would like to mess with complex state structures, we can always make sure that only what needs to be triggered is triggered and optimize the amount of times we need to validate the state.

Step 5: Code Splitting and Lazy Loading

Implement Code Splitting: Use React.lazy and Suspense to load components only when needed. Configure Webpack to split bundles and optimize loading times.
Lazy Load Routes and Components: Ensure that only essential components and routes are loaded upfront, with the rest being lazy-loaded as needed.

Step 6: Bundle Analysis and Optimization

Analyze Bundle Size: Use tools like Webpack Bundle Analyzer to visualize your bundle size and identify large dependencies.
Remove Unused Dependencies: Eliminate unused libraries, components, and imports that are unnecessarily increasing your bundle size.

Step 7: Optimize API Calls and Asynchronous Operations

Debounce and Throttle: Implement debouncing or throttling for frequent API calls or event handlers to reduce the load on the server and improve responsiveness.
Batch Actions: Where possible, batch Redux actions to minimize the number of state updates and reduce re-renders.

Step 8: Optimize Rendering and State Updates

Memoize Expensive Computations: Use useMemo and useCallback to memoize expensive computations or function definitions that are causing performance bottlenecks.
Selector Optimization: Use reselect to create efficient, memoized selectors that prevent unnecessary recalculations of derived state.

Step 9: Image and Asset Optimization

Optimize Images: Use modern formats like WebP, and tools like Squoosh to compress images without sacrificing quality. Implement lazy loading for images.
Optimize Fonts and Static Assets: Reduce the size and load time of fonts and other static assets using CDNs, caching, and compression.

Step 10: Continuous Monitoring and Iterative Improvement

Set Up Monitoring: Implement performance monitoring tools like New Relic, Sentry, or LogRocket to continuously monitor application performance in production.
Iterate and Improve: Regularly revisit the performance metrics and user feedback to identify new bottlenecks. Prioritize optimizations based on impact and feasibility, and iterate on the process.

By following this protocol, you can systematically identify and optimize problematic areas in your React application, ensuring that it performs efficiently and meets user expectations.