Bolt performance

Font Loading Causing Layout Shift - FOUT or FOIT

Fonts load slowly causing text to flash or shift layout (Cumulative Layout Shift). Users see unstyled text briefly before custom font loads.

This impacts Core Web Vitals and user experience.

Error Messages You Might See

Cumulative Layout Shift > 0.25 Font blocking render for 3+ seconds Text remains invisible while custom font loads FOUT/FOIT causing layout thrashing
Cumulative Layout Shift > 0.25Font blocking render for 3+ secondsText remains invisible while custom font loadsFOUT/FOIT causing layout thrashing

Common Causes

  1. Loading fonts from CDN without preload
  2. Large font files not optimized or subsetted
  3. Font-display not set to optimal value
  4. Loading too many font variations
  5. Self-hosted fonts not configured for preload

How to Fix It

Add preload to head:

Use font-display: swap in @font-face to prevent invisible text

Subset fonts: include only characters you use

Use Next.js font optimization: import { Poppins } from 'next/font/google'

Limit to 2-3 font families max

Real developers can help you.

Jen Jacobsen Jen Jacobsen I’m a Full-Stack Developer with over 10 years of experience building modern web and mobile applications. I enjoy working across the full product lifecycle — turning ideas into real, well-built products that are intuitive for users and scalable for businesses. I particularly enjoy building mobile apps, modern web platforms, and solving complex technical problems in a way that keeps systems clean, reliable, and easy to maintain. Victor Denisov Victor Denisov Developer Matt Butler Matt Butler Software Engineer @ AWS 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. MFox MFox Full-stack professional senior engineer (15+years). Extensive experience in software development, qa, and IP networking. David Olverson David Olverson Solo dev shipping production apps with AI-assisted development. I specialize in rescuing broken Lovable/Bolt/Cursor builds and taking them to production. 10+ apps shipped including SaaS CRMs, gaming platforms, real estate tools, and Discord bots. Stack: Next.js 16, TypeScript, Tailwind CSS, FastAPI, PostgreSQL, Prisma. I use Claude Code with 50+ custom skills for rapid delivery. Average turnaround: 2-4 weeks from broken prototype to production. Prakash Prajapati Prakash Prajapati I’m a Senior Python Developer specializing in building secure, scalable, and highly available systems. I work primarily with Python, Django, FastAPI, Docker, PostgreSQL, and modern AI tooling such as PydanticAI, focusing on clean architecture, strong design principles, and reliable DevOps practices. I enjoy solving complex engineering problems and designing systems that are maintainable, resilient, and built to scale. 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. AUXLE AUXLE I am a Full Stack Developer experienced in building Websites, Web apps and Cross Platform Mobile Apps for Startups and Companies. 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.

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Frequently Asked Questions

What's the best font-display value?

swap: shows system font immediately, updates when custom loads (best UX). fallback: wait 100ms then show system

Should I self-host or use CDN?

Self-host for control and speed. CDN (Google Fonts) if you want simplicity

How do I minimize font downloads?

Subset fonts to used characters, use variable fonts for multiple weights, limit to necessary fonts

Related Bolt Issues

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