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.

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. Kingsley Omage Kingsley Omage Fullstack software engineer passionate about AI Agents, blockchain, LLMs. 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. BurnHavoc BurnHavoc Been around fixing other peoples code for 20 years. 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. 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. Mehdi Ben Haddou Mehdi Ben Haddou - Founder of Chessigma (1M+ users) & many small projects - ex Founding Engineer @Uplane (YC F25) - ex Software Engineer @Amazon and @Booking.com PawelPloszaj PawelPloszaj I'm fronted developer with 10+ years of experience with big projects. I have small backend background too Jacek Rozanski Jacek Rozanski Senior PHP/Symfony developer and DevOps engineer with 20+ years of professional experience, running opcode.pl (web development agency, est. 2004). Day job: I'm the sole backend developer at merketing company where I own and maintain 11 PHP/Symfony microservices on AWS (ECS Fargate, RDS, S3, CloudFront), handle the full CI/CD pipeline (Bitbucket Pipelines, Docker), and manage monitoring with Sentry and CloudWatch. These services handle high request volumes in production every month. What I bring to AI-built apps: - I audit and fix security issues (OWASP methodology), performance bottlenecks, and architectural problems in codebases generated by Cursor, Claude Code, Lovable, Bolt, and v0 - I refactor AI-generated prototypes into production-grade applications with proper error handling, testing, and clean architecture (SOLID, DDD, hexagonal architecture) - I set up the infrastructure AI tools don't touch: AWS hosting, CI/CD pipelines, automated deployments, database optimization, monitoring, and alerting - I integrate external services: payment providers, email systems, partner APIs, SSO/auth Tech stack: PHP 8.x, Symfony, React, Next.js, PostgreSQL, MySQL, Docker, AWS (ECS, RDS, S3, SQS/SNS, CloudFront), Terraform, Supabase. I also use AI tools daily (Claude Code, Cursor) in my own workflow, so I understand both the strengths and the gaps in AI-generated code. Based in Poland (CET timezone). Available for async work and calls during EU/US business hours. Anthony Akpan Anthony Akpan Developer with 8 years of experience building softwares fro startups

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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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