Running and building a Vue app - Performance & Optimization

Performance: Running and building a Vue app

HIGH IMPACT

This affects the initial page load speed and runtime performance by controlling how the Vue app is compiled, bundled, and served.

Building a Vue app for production deployment

Vue

vue-cli-service build --mode production

Production mode enables minification, tree shaking, and optimizations to reduce bundle size and improve load speed.

📈 Performance Gainreduces bundle size by 50-70%, speeds up LCP by 1-2 seconds

Building a Vue app for production deployment

Vue

vue-cli-service build --mode development

Building in development mode includes extra debugging code and unminified files, increasing bundle size and slowing load.

📉 Performance Costadds 300-500kb to bundle, blocks rendering longer, delays LCP by 1-2 seconds

Performance Comparison

Pattern	DOM Operations	Reflows	Paint Cost	Verdict
Development build	Normal DOM nodes	Multiple reflows due to unoptimized scripts	Higher paint cost due to large CSS/JS	[X] Bad
Production build with optimizations	Normal DOM nodes	Minimal reflows with optimized scripts	Lower paint cost due to smaller CSS/JS	[OK] Good

Rendering Pipeline

The Vue build process affects how JavaScript and CSS are loaded and parsed, impacting style calculation, layout, and paint stages in the browser.

→Style Calculation

→Layout

→Paint

→Composite

⚠️ BottleneckLarge unoptimized bundles delay JavaScript parsing and style calculation, blocking initial paint.

Core Web Vital Affected

LCP

This affects the initial page load speed and runtime performance by controlling how the Vue app is compiled, bundled, and served.

Optimization Tips

1Always build Vue apps in production mode for deployment to reduce bundle size.

2Enable hot module replacement during development to speed up code updates.

3Use code splitting and lazy loading to improve initial load performance.

Performance Quiz - 3 Questions

What is the main performance benefit of building a Vue app in production mode?

A Faster hot module replacement

B More detailed error messages

C Smaller bundle size and faster initial load

D Automatic CSS animations

DevTools: Performance

How to check: Open DevTools Performance tab, record page load, and analyze scripting and rendering times.

What to look for: Look for long scripting tasks and large layout or paint times indicating unoptimized bundles.