Deepak Singh Rawat’s Post

🚀 Lazy Loading in React.js: A Simple Optimisation That Makes a Huge Difference As React applications scale, performance becomes a critical concern. One of the most effective, yet often overlooked, optimisations is lazy loading ⚡ In many React apps, we unintentionally ship all route components in the initial bundle 📦 Even when the user lands only on the Home page, pages like About, Services, and Contact are already downloaded. This increases load time, delays interactivity, and impacts user experience — especially on slower networks 🌐 In this small demo, I implemented route-based lazy loading using React.lazy() and Suspense. 🔍 What changed after lazy loading? On initial load (/), only Home.jsx is downloaded Other files are downloaded only when the user navigated to them Using React.lazy() and Suspense, we can 👇 🔹 Split route components into separate JS chunks 🔹 Reduce initial bundle size 🔹 Improve performance metrics like TTI and LCP 🔹 Deliver a smoother, faster user experience ✨ This approach is especially powerful for: ✅ Route-based pages ✅ Large dashboards ✅ Feature-heavy admin panels ✅ Heavy libraries like charts or editors 📊 That said, lazy loading should be used thoughtfully 🧠 Lazy loading critical or above-the-fold UI can backfire. Like most optimisations, balance is key ⚖️ If you’re building scalable React or Next.js applications, mastering route-based lazy loading is a must 💡 Happy coding 🚀👨💻👩💻 #ReactJS #LazyLoading #CodeSplitting #WebPerformance #FrontendDevelopment #JavaScript #NextJS #MERNStack #SoftwareEngineering #WebDevelopment

In early days of development, I once built a simple React dashboard - just filters and a list - and a single checkbox caused 127 re-renders. My laptop fan sounded like a jet taking off 😄. That’s when I realized something important: "React isn’t slow - my understanding of it was" The app worked fine with 10 items - but with 100, scrolling felt like molasses. Why? Because React will re-render anything that looks “different” - even when it shouldn’t matter. Here are the real culprits I found: 🔹 New objects in render Passing freshly created objects makes React think something changed - even if it didn’t. 🔹 Inline functions Every arrow function in JSX creates a new reference - and that triggers re-renders everywhere. 🔹 One big context object If a context contains everything, changing anything re-renders everything. 🔹 State updates in loops Updating state inside a loop can literally trigger 100 re-renders in one effect. 🔹 Not memoizing expensive components React.memo isn’t always the answer - but in the right places, it stops needless work. But here’s the bigger lesson: 👉 Re-renders only matter when rendering is expensive. Measure first. Optimize second. React DevTools Profiler isn’t optional - it’s the difference between guessing and knowing what’s slowing you down. If you build large React apps and want smoother performance without premature optimization, I broke this down in detail. 🔗 Medium Link in the first comment 👇 #codewithsaad #appzivo #ReactJS #FrontendDevelopment #WebPerformance #JavaScript #SoftwareEngineering #TechLeadership #ProductThinking #ReactProfiler

“Your React app is slow because of too many re-renders.” Often true… and often the wrong diagnosis. 🧠⚛️ Myth: re-renders are inherently bad. Reality: React re-rendering is cheap; expensive work inside renders is not. The UI gets slow when renders trigger heavy computations, layout thrash, or large component trees doing real work. What I see in production: 1) Unstable props cause cascading updates Inline objects/functions create new references → memo breaks → more work. Use useCallback/useMemo only where it reduces churn, not by default. 🔁 2) “Memo everywhere” backfires React.memo adds comparison overhead and hides data flow issues. If props change every time, memo is noise. 🧩 3) The real killers: effects + fetching + parsing Extra useEffect loops, derived state, and client-side heavy transforms. Move compute to selectors, server, or workers. 🧰 4) Measure, don’t guess React DevTools Profiler + why-did-you-render (selectively) will tell you if the bottleneck is render, commit, or JS work. 📈 Practical takeaway: optimize references and data flow first, then isolate expensive components, then memo strategically. Where have you seen “re-render panic” hide the actual root cause? 👇 #react #javascript #frontend #performance #nextjs

My React app got faster after I stopped guessing and followed this “recipe” 🍳 1️⃣ Measure first (so you don’t guess) Before optimizing, I measured. React DevTools Profiler → shows which components re-render a lot Chrome DevTools / Lighthouse → shows slow load + long tasks Bundle Analyzer → shows what’s making your JS bundle big 2️⃣ Reduce unnecessary re-renders (usually the biggest win) Re-render = React re-draws UI again. What helped: Keep state close to where it’s used (avoid unnecessary global state) Avoid passing new props each render (like {} or () => {} created inline) Use these only when they actually help: useMemo → keep the same object/array/value instead of recreating it every render useCallback → keep the same function reference so memoized children don’t re-render React.memo → prevents re-render when props didn’t really change 👉 Simple rule: useMemo / useCallback are worth it only if they stop real re-renders you can see in the Profiler. 3️⃣ Speed up big lists / tables Rendering 1000+ rows/cards = heavy UI. Use: react-window or react-virtualized → Render only what’s visible on screen (virtualization) 4️⃣ Load less code on first page load If your app feels slow initially, you’re shipping too much JS. Use: Dynamic imports (load code only when needed) React.lazy + Suspense In Next.js: next/dynamic for heavy components (charts, editors) 5️⃣ Make typing & search feel smooth If the UI feels laggy while typing/filtering: Debounce input Use startTransition / useDeferredValue to keep UI responsive 🧠 Easy way to remember ->✅ Measure (Profiler / Lighthouse) → ✅ Stop extra re-renders (useMemo, useCallback, React.memo) → ✅ Virtualize lists (react-window) → ✅ Lazy load (dynamic import, React.lazy) In your projects, what’s the bigger pain: slow first load or too many re-renders? #reactjs #frontend #javascript #webdevelopment #softwareengineering #performance #webperformance #reactdeveloper #typescript #nextjs #reacthooks

This is a solid checklist and I agree with the core idea: measure first, don't guess. Simple rule to follow if an optimization doesn't show up in React DevTools or Lighthouse, it's probably not worth it. Performance is a process, not a hack. #React #NextJS #FrontendPerformance #WebPerformance

React 19.2 introduces <Activity />, a new way to think about component lifecycle and performance in React. It helps keep components alive, preserve state, and make navigation feel instant — without complex workarounds. I wrote a short Medium article explaining how it works, why it matters, and where it fits best in real apps. Read here 👉 https://lnkd.in/dNKQ-6SZ #ReactJS #React19 #Frontend #JavaScript #WebPerformance #WebDevelopment

🚀 React Performance Optimization Step by Step (Made Simple) A React app doesn’t become slow overnight. It becomes slow when we ignore small performance mistakes. Let’s break React performance optimization into clear, practical steps 👇 🔹 Step 1: Understand Why Re-renders Happen React re-renders a component when: • State changes • Props change • Parent component re-renders 👉 Rule: Not every re-render is bad unnecessary ones are. 🔹 Step 2: Stop Unnecessary Re-renders Use these tools only when needed: • React.memo → prevents child re-render if props don’t change • useCallback → memoizes functions • useMemo → memoizes expensive calculations 👉 Optimization without a problem can create more problems. 🔹 Step 3: Keep State Close to Where It’s Used Avoid putting everything in global state. • Local state → local components • Global state → truly shared data 👉 Less shared state = fewer re-renders. 🔹 Step 4: Optimize Expensive Calculations If a calculation: • Runs inside loops • Filters large arrays • Does heavy processing 👉 Wrap it in useMemo to avoid recalculating on every render. 🔹 Step 5: Lazy Load Components Don’t load everything at once. • Use React.lazy • Load heavy components only when needed 👉 Faster initial load = better user experience. 🔹 Step 6: Handle Large Lists Properly Rendering 1,000+ items at once is expensive. • Use list virtualization (react-window, react-virtualized) • Render only visible items 👉 Massive performance improvement. 🔹 Step 7: Measure Before You Optimize Never guess performance issues. • Use React DevTools Profiler • Identify slow components • Optimize only where it matters 👉 Measure → Optimize → Measure again. 💡 Final Thought React performance optimization isn’t about writing clever code. It’s about removing unnecessary work. Clean code + smart rendering = fast React apps ⚡ What’s the first performance issue you usually notice in React projects? Let’s discuss 👇 #ReactJS #FrontendDevelopment #WebPerformance #JavaScript #CleanCode #SoftwareEngineering

What actually helps speed up a web application (from real-world React projects) 🚀 After working on several large-scale React apps, I’ve noticed one thing: performance problems are rarely solved by one magic trick. It’s usually a set of boring—but effective—decisions. Here’s what really makes a difference 👇 🔹 Measure before optimizing Use Lighthouse, Web Vitals, and the React Profiler. If you don’t know what’s slow, you’ll optimize the wrong thing. 🔹 Reduce unnecessary re-renders Memoization (useMemo, useCallback, React.memo) is powerful — but only when applied intentionally, not everywhere “just in case”. 🔹 Code splitting & lazy loading Load only what the user actually needs right now. Routes, heavy components, charts — all great candidates. 🔹 Smart state management Global state is expensive. Keep state as local as possible and avoid overusing context for frequently changing data. 🔹 Network > JavaScript Caching, compression, and reducing request count often give bigger wins than micro-optimizing JS. 🔹 Performance is a product feature If users feel the app is fast, it is fast — even if the code isn’t perfect. Speed is not about tricks. It’s about discipline, measurement, and trade-offs. Curious — what gave you the biggest performance win in your last project? #frontend #react #performance #webdevelopment #javascript #seniorfrontend #softwareengineering #webperf

My Next.js app felt slow. Not broken. Just… slow. And the fix wasn’t a rewrite. It was removing bad defaults. Here’s what actually moved the needle 👇 → Shipped less client JavaScript → Stopped fetching data in the browser by habit → Optimized images properly (LCP matters) → Lazy-loaded heavy UI (charts, modals, dashboards) → Used caching intentionally, not randomly The biggest lesson? → Performance isn’t magic → It’s architecture + discipline → Next.js rewards server-first thinking If your app feels “almost fast,” this is probably why. 🔁 Share this with someone who says “Next.js is slow.” #Nextjs #WebPerformance #FrontendDevelopment #Reactjs #JavaScript #TypeScript #WebDev #PerformanceOptimization #CoreWebVitals #FrontendEngineer #SoftwareEngineering #BuildInPublic #DevTips #TechCareers #Programming

Why React Re-Renders (And When It Shouldn’t) React feels fast when everything works smoothly. But when an app starts lagging, flickering, or feeling “heavy,” the root cause is often the same: unnecessary re-renders. React doesn’t randomly re-render components. It does it for one simple reason—something changed. A component re-renders when: • Its state changes • Its props change • Its parent re-renders • Its context updates That’s React doing its job. The problem starts when more changes happen than necessary. Where Re-Renders Become a Performance Issue If one small state update causes dozens of components to re-render, users feel it. Animations stutter. Input fields lag. Pages feel slow—even though the backend is fine. This usually happens when: • State is stored too high in the component tree • Props are recreated on every render • Expensive components aren’t memoized • Lists re-render when only one item changes React Is Efficient—But Not Psychic React compares the previous and current virtual DOM to decide what to update. But if everything looks new to React, it will re-render—even if nothing meaningful changed. That’s why stable references (memoization, callbacks, proper state placement) matter. They tell React what truly changed and what didn’t. When Re-Renders Are Actually a Good Thing Re-renders are not the enemy. They keep the UI in sync with data. The goal isn’t to eliminate them—it’s to prevent unnecessary ones. Well-optimized React apps don’t re-render less. They re-render only what matters. That’s the difference between an app that feels instant… and one that feels heavy. #React #MERN #WebPerformance #FrontendDevelopment #JavaScript #SoftwareEngineering #WebApps