Bolt performance

Large Bundle Size - App Loads Slowly

Your JavaScript bundle is very large (over 500KB), making the app slow to load. First Contentful Paint takes several seconds even on good connections.

Users on slow networks experience long loading times.

Error Messages You Might See

Bundle size 750KB (over limit) First Contentful Paint 8 seconds Large Cumulative Layout Shift Slow interaction to Next Paint
Bundle size 750KB (over limit)First Contentful Paint 8 secondsLarge Cumulative Layout ShiftSlow interaction to Next Paint

Common Causes

  1. Importing entire library when only small part needed
  2. Large image assets embedded in bundle instead of loaded separately
  3. Unused code not being tree-shaken by build tool
  4. Moment.js or similar heavy date libraries (use date-fns, dayjs instead)
  5. Loading all routes upfront instead of code splitting by route

How to Fix It

Use tree-shakeable imports: import { map } from 'lodash-es' not import lodash

Lazy load heavy components: const Component = dynamic(() => import('@/components/Heavy'))

Replace heavy libraries: moment.js -> date-fns or dayjs, @apollo/client -> urql

Optimize images: use next/image, convert to WebP, serve appropriate sizes

Enable code splitting in Next.js config (automatic for routes)

Real developers can help you.

AUXLE AUXLE I am a Full Stack Developer experienced in building Websites, Web apps and Cross Platform Mobile Apps for Startups and Companies. ISHANTDEEP SINGH ISHANTDEEP SINGH Senior Software Engineer with 7+ years of experience in React, JavaScript, TypeScript, Next.js, and Node.js. I’ve also worked as a tech lead for startups, owning end-to-end technical execution including architecture, development, scaling, and delivery. I bring a strong mix of hands-on coding, product thinking, and technical leadership, and I’m comfortable building products from scratch as well as improving and scaling existing systems. Luca Liberati Luca Liberati I work on monoliths and microservices, backends and frontends, manage K8s clusters and love to design apps architecture Milan Surelia Milan Surelia Milan Surelia is a Mobile App Developer with 5+ years of experience crafting scalable, cross-platform apps at 7Span and Meticha. At 7Span, he engineers feature-rich Flutter apps with smooth performance and modern UI. As the Co-Founder of Meticha, he builds open-source tools and developer-focused products that solve real-world problems. Expertise: 💡 Developing cross-platform apps using Flutter, Dart, and Jetpack Compose for Android, iOS, and Web. 🖋️ Sharing insights through technical writing, blogging, and open-source contributions. 🤝 Collaborating closely with designers, PMs, and developers to build seamless mobile experiences. Notable Achievements: 🎯 Revamped the Vepaar app into Vepaar Store & CRM with a 2x performance boost and smoother UX. 🚀 Launched Compose101 — a Jetpack Compose starter kit to speed up Android development. 🌟 Open source contributions on Github & StackOverflow for Flutter & Dart 🎖️ Worked on improving app performance and user experience with smart solutions. Milan is always happy to connect, work on new ideas, and explore the latest in technology. rayush33 rayush33 JavaScript (React.js, React Native, Node.js) Developer with demonstrated industry experience of 4+ years, actively looking for opportunities to hone my skills as well as help small-scale business owners with solutions to technical problems Alvin Voo Alvin Voo I’ve watched the tech landscape evolve over the last decade—from the structured days of Java Server Pages to the current "wild west" of Agentic-driven development. While AI can "vibe" a frontend into existence, I specialize in the architecture that keeps it from collapsing. My expertise lies in the critical backend infrastructure: the parts that must be fast, secure, and scalable. I thrive on high-pressure environments, such as when I had only three weeks to architect and launch an Ethereum redemption system with minimal prior crypto knowledge, turning it into a major revenue stream. What I bring to your project: Forensic Debugging: I don't just "patch" bugs; I use tools like Datadog and Explain Analyzers to map out bottlenecks and resolve root causes—like significantly reducing memory usage by optimizing complex DB joins. Full-Stack Context: Deep experience in Node.js and React, ensuring backends play perfectly with mobile and web teams. Sanity in the Age of AI: I bridge the gap between "best practices" and modern speed, ensuring your project isn't just built fast, but built to last. Matt Butler Matt Butler Software Engineer @ AWS Bastien Labelle Bastien Labelle Full stack dev w/ 20+ years of experience Yovel Cohen Yovel Cohen I got a lot of experience in building Long-horizon AI Agents in production, Backend apps that scale to millions of users and frontend knowledge as well. Costea Adrian Costea Adrian Embedded Engineer specilizing in perception systems. Latest project was a adas camera calibration system.

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Frequently Asked Questions

What's a good target bundle size?

JavaScript: <200KB. With gzip: <50KB. For comparison, heavy frameworks are ~200KB

How do I check actual bundle size?

npm run build shows Next.js Size. Use webpack-bundle-analyzer for detailed breakdown

What about image sizes?

Use next/image for automatic optimization. Aim for <100KB total images, <30KB per image

Related Bolt Issues

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