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.

Anthony Akpan Anthony Akpan Developer with 8 years of experience building softwares fro startups Dor Yaloz Dor Yaloz SW engineer with 6+ years of experience, I worked with React/Node/Python did projects with React+Capacitor.js for ios Supabase expert Basel Issmail Basel Issmail ’m a Senior Full-Stack Developer and Tech Lead with experience designing and building scalable web platforms. I work across the full development lifecycle, from translating business requirements into technical architecture to delivering reliable production systems. My work focuses on modern web technologies, including TypeScript, Angular, Node.js, and cloud-based architectures. I enjoy solving complex technical problems and helping teams turn product ideas and prototypes into working platforms that can grow and scale. In addition to development, I often collaborate closely with product managers, business analysts, designers, and QA teams to ensure that solutions align with both technical and business goals. I enjoy working with startups and product teams where I can contribute both as a hands-on engineer and as a technical partner in designing and delivering impactful software. Simon A. Simon A. I'm a backend developer building APIs, emulators, and interactive game systems. Professionally, I've developed Java/Spring reporting solutions, managed relational and NoSQL databases, and implemented CI/CD workflows. Bastien Labelle Bastien Labelle Full stack dev w/ 20+ years of experience prajwalfullstack prajwalfullstack Hi Im a full stack developer, a vibe coded MVP to Market ready product, I'm here to help Matthew Butler Matthew Butler Systems Development Engineer @ Amazon Web Services Rudra Bhikadiya Rudra Bhikadiya I build and fix web apps across Next.js, Node.js, and DBs. Comfortable jumping into messy code, broken APIs, and mysterious bugs. If your project works in theory but not in reality, I help close that gap. Vlad Temian Vlad Temian 15+ years shipping production infrastructure for startups. Former CTO at qed.builders (acquired by The Sandbox). Cursor ambassador and agentic tooling builder. I've scaled systems, automated deployments, and built observability tools for AI coding workflows. I specialize in taking vibe-coded apps from broken prototype to production-ready: fixing Supabase auth/RLS, Stripe integrations, deployment pipelines, and cleaning up AI-generated spaghetti. I build tools in this space (agentprobe, claudebin, micode) and understand both sides: how AI generates code and why it breaks. https://blog.vtemian.com/ Meïr Ankri Meïr Ankri Full-stack developer specializing in React / Next.js / Node.js with 6+ years of experience. I've worked across various sectors including automotive (Reezocar/Société Générale), healthcare (Medical Link SaaS), and e-commerce (Glasman). I build web apps end-to-end, from architecture to production, with a focus on scalability, performance, and code quality. I also mentor junior developers and contribute to technical decisions and code reviews.

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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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