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

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.

PawelPloszaj PawelPloszaj I'm fronted developer with 10+ years of experience with big projects. I have small backend background too Richard McSorley Richard McSorley Full-Stack Software Engineer with 8+ years building high-performance applications for enterprise clients. Shipped production systems at Walmart (4,000+ stores), Cigna (20M+ users), and Arkansas Blue Cross. 5 patents in retail/supply chain tech. Currently focused on AI integrations, automation tools, and TypeScript-first architectures. MFox MFox Full-stack professional senior engineer (15+years). Extensive experience in software development, qa, and IP networking. 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 Taufan Taufan I’m a product-focused engineer and tech leader who builds scalable systems and turns ideas into production-ready platforms. Over the past years, I’ve worked across startups and fast-moving teams, leading backend architecture, improving system reliability, and shipping products used by thousands of users. My strength is not just writing code — but connecting product vision, technical execution, and business impact. Nam Tran Nam Tran 10 years as fullstack developer 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. Franck Plazanet Franck Plazanet I am a Strategic Engineering Leader with over 8 years of experience building high-availability enterprise systems and scaling high-performing technical teams. My focus is on bridging the gap between complex technology and business growth. Core Expertise: 🚀 Leadership: Managing and coaching teams of 15+ engineers, fostering a culture of accountability and continuous improvement. 🏗️ Architecture: Enterprise Core Systems, Multi-system Integration (ERP/API/ETL), and Core Database Structure. ☁️ Cloud & Scale: AWS Expert; architected systems handling 10B+ monthly requests and managing 100k+ SKUs. 📈 Business Impact: Aligning tech strategy with P&L goals to drive $70k+ in monthly recurring revenue. I thrive on "out-of-the-box" thinking to solve complex technical bottlenecks and am always looking for ways to use automation to improve business productivity. 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. Matt Butler Matt Butler Software Engineer @ AWS

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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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