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Discover why large files slow down Lovable load times, learn to optimize performance, and master best practices for asset sizes.
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Large files slow Lovable load times because they increase the number of bytes the browser must download and the time the browser must spend parsing/decoding them, which directly delays first meaningful paint and JavaScript execution; in Lovable this also affects Preview and GitHub sync (larger uploads, slower pushes), so even without local CLI work you’ll see slower developer preview, slower publish, and more memory/CPU pressure in users’ browsers.
Paste the following prompt into Lovable’s chat to create files and wire a visible reporter into your app. This does NOT change assets — it only detects and displays large resources at runtime so you can see what’s slowing load times.
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// Create src/constants/assetThresholds.ts
// This sets the threshold in bytes (example: 500_000 = 500KB)
export const ASSET_SIZE_THRESHOLD = 500000;
// Create src/components/AssetSizeReporter.tsx
// A lightweight overlay that reads performance resource timings and lists resources above threshold
import React, {useEffect, useState} from 'react';
import {ASSET_SIZE_THRESHOLD} from '../constants/assetThresholds';
export default function AssetSizeReporter() {
const [largeResources, setLargeResources] = useState([]);
useEffect(() => {
function collect() {
// performance.getEntriesByType returns PerformanceResourceTiming entries
const entries = (performance.getEntriesByType('resource') || []);
const list = entries
.map(e => ({
name: e.name,
size: e.transferSize || 0,
duration: Math.round(e.duration),
type: e.initiatorType || 'resource'
}))
.filter(r => r.size >= ASSET_SIZE_THRESHOLD)
.sort((a, b) => b.size - a.size);
setLargeResources(list);
}
// collect after load and periodically (helps spot late-loaded fonts/images)
collect();
const id = setInterval(collect, 3000);
return () => clearInterval(id);
}, []);
if (!largeResources.length) return null;
return (
<div style={{
position: 'fixed',
right: 12,
bottom: 12,
zIndex: 9999,
maxWidth: 420,
background: 'rgba(0,0,0,0.75)',
color: 'white',
padding: 12,
borderRadius: 8,
fontSize: 12,
lineHeight: '1.2',
boxShadow: '0 6px 18px rgba(0,0,0,0.3)'
}}>
<div style={{fontWeight: 700, marginBottom: 8}}>Large resources detected</div>
<div style={{maxHeight: 220, overflow: 'auto'}}>
{largeResources.map(r => (
<div key={r.name} style={{marginBottom: 8}}>
<div style={{fontWeight: 600}}>{r.name.split('?')[0].split('/').slice(-1)[0]}</div>
<div style={{opacity: 0.9}}>~{Math.round(r.size / 1024)} KB • {r.type} • {r.duration} ms</div>
</div>
))}
</div>
</div>
);
}
// Update src/App.tsx (or your root entry) to mount the reporter near the top-level layout
// Insert: import AssetSizeReporter from './components/AssetSizeReporter';
// Then add <AssetSizeReporter /> inside your main App component (e.g., next to your Router or Layout)
This prompt helps an AI assistant understand your setup and guide you through the fix step by step, without assuming technical knowledge.
Move heavy binary assets out of the repository and serve them from a blob/CDN (Supabase, S3, Cloudinary), add Lovable Secrets for storage credentials, update the app to request signed URLs and lazy-load/stream assets, and—if files are already >50MB—export to GitHub and enable Git LFS outside Lovable.
// Please scan the repository file tree and list all files larger than 1MB.
// Return a short plain list: "<path> — <size in MB>".
// This helps me decide which assets to move out of the repo.
// Update code to read storage secrets from environment variables.
// Create file src/lib/storageClient.ts
// // src/lib/storageClient.ts
import { createClient } from '@supabase/supabase-js'
// // Read from environment — Lovable: use Secrets UI to set SUPABASE_URL and SUPABASE_KEY
const supabaseUrl = process.env.SUPABASE_URL
const supabaseKey = process.env.SUPABASE_KEY
export const supabase = createClient(supabaseUrl!, supabaseKey!)
// // helper to create public or signed URL
export async function getSignedUrl(path: string, expires = 60) {
// // returns a URL string
const { data, error } = await supabase.storage
.from('public')
.createSignedUrl(path, expires)
if (error) throw error
return data.signedURL
}
// Create file src/components/LazyImage.tsx
// // src/components/LazyImage.tsx
import React, { useEffect, useState } from 'react'
import { getSignedUrl } from '../lib/storageClient'
export default function LazyImage({ path, alt, sizes, srcSet }) {
const [src, setSrc] = useState<string | null>(null)
useEffect(() => {
let mounted = true
getSignedUrl(path, 300).then(url => {
if (mounted) setSrc(url)
})
return () => { mounted = false }
}, [path])
return (
<img
src={src || '/placeholder-low-res.png'}
alt={alt}
loading="lazy"
decoding="async"
sizes={sizes}
srcSet={srcSet}
style={{ maxWidth: '100%', height: 'auto' }}
/>
)
}
// // Now update files that render heavy images – e.g., update src/pages/Gallery.tsx
// // Replace direct <img src="/assets/huge.jpg" /> with:
// // <LazyImage path="images/huge.jpg" alt="..." />
// Update src/App.tsx (or the main router file) to lazy-load heavy pages
// // src/App.tsx
import React, { Suspense, lazy } from 'react'
import { BrowserRouter as Router, Route, Switch } from 'react-router-dom'
// // lazy-load the heavy gallery page
const Gallery = lazy(() => import('./pages/Gallery'))
const Home = lazy(() => import('./pages/Home'))
export default function App() {
return (
<Router>
<Suspense fallback={<div>Loading...</div>}>
<Switch>
<Route path="/gallery" component={Gallery} />
<Route path="/" component={Home} />
</Switch>
</Suspense>
</Router>
)
}
// For each file reported as large (paste the list from the scan), replace direct repo usage.
// Example: replace <img src="/assets/large.jpg" /> with <LazyImage path="images/large.jpg" />
// Update imports that use require('/assets/large.mp4') to fetch from storage endpoints instead.
// Please edit these files directly and show diffs for review.
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Optimize assets by: always serve appropriately sized, compressed formats (WebP/AVIF) via responsive srcset, move bulky binaries to external storage/CDN (Supabase Storage, S3, or a real CDN), run build-time asset compression in CI (GitHub Actions) instead of keeping heavy originals in the repo, lazy-load noncritical media, and store credentials in Lovable Secrets. Below are Lovable prompts you can paste into Lovable chat to implement these best practices across your app.
Paste this prompt into Lovable to create/update a reusable image component that emits srcset, sizes, WebP fallback, and lazy loading.
// create src/components/ResponsiveImage.tsx
// This component emits srcset/sizes + webp fallback + loading="lazy"
/* // React/TSX example, adjust imports to match your project */
import React from "react";
type Props = {
src: string;
alt?: string;
widths?: number[]; // e.g. [320,640,1024]
sizes?: string; // e.g. "(max-width: 600px) 100vw, 50vw"
className?: string;
};
export default function ResponsiveImage({ src, alt = "", widths = [320,640,1024], sizes = "100vw", className }: Props) {
const extIdx = src.lastIndexOf(".");
const base = src.substring(0, extIdx);
const ext = src.substring(extIdx + 1);
const srcset = widths.map(w => `${base}-${w}.${ext} ${w}w`).join(", ");
const webpSrcset = widths.map(w => `${base}-${w}.webp ${w}w`).join(", ");
return (
<picture>
<source type="image/webp" srcSet={webpSrcset} sizes={sizes} />
<img src={src} srcSet={srcset} sizes={sizes} alt={alt} className={className} loading="lazy" decoding="async" />
</picture>
);
}
Prompt for Lovable: "Create src/lib/storageClient.ts and update code that serves media to use signed URLs. Set STORAGE_BUCKET and STORAGE_KEY in Lovable Secrets."
// create src/lib/storageClient.ts
// Replace with your provider's SDK usage; we read keys from process.env
export function getSignedUrl(path: string) {
// // Example placeholder logic. Replace with SDK calls in your repo.
const bucket = process.env.STORAGE_BUCKET;
const base = process.env.STORAGE_BASE_URL;
// // Ensure you set STORAGE_BUCKET and STORAGE_BASE_URL in Lovable Secrets
return `${base}/${bucket}/${path}`;
}
Prompt for Lovable: "Add GitHub Action that compresses images on push. This runs outside Lovable in GitHub CI." (This uses GitHub Actions — no terminal inside Lovable required.)
// create .github/workflows/optimize-assets.yml
// Runs on pushes to main, uses Node to run a script that compresses assets.
name: Optimize Assets
on: [push]
jobs:
optimize:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v4
- name: Setup Node
uses: actions/setup-node@v4
with:
node-version: 18
- name: Install
run: npm ci
- name: Run asset optimizer
run: node scripts/optimize-assets.js
// create scripts/optimize-assets.js
// Use imagemin packages when this runs in GitHub Actions. This file is a coordinator.
const fs = require("fs");
const path = require("path");
// // Add lightweight logic to compress images in assets/images and write optimized variants.
// // In CI you should add imagemin packages to package.json so npm ci installs them.
console.log("Placeholder optimizer — install imagemin in package.json to compress files in CI.");
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