Bundle analysis and tree shaking in Vue - Performance & Optimization

Performance: Bundle analysis and tree shaking

HIGH IMPACT

This concept affects the page load speed by reducing the JavaScript bundle size and improving initial download and parse time.

Including only necessary Vue components and libraries in the bundle

Vue

import { VBtn, VCard } from 'vuetify/components';
export default {
  components: { VBtn, VCard }
};

Imports only used components, enabling tree shaking to remove unused code.

📈 Performance Gainsaves 250kb+ in bundle size, reduces blocking time by 100ms

Including only necessary Vue components and libraries in the bundle

Vue

import * as Vuetify from 'vuetify';
export default {
  components: { ...Vuetify }
};

Imports the entire Vuetify library, including unused components, increasing bundle size.

📉 Performance Costadds 300kb+ to bundle, blocks rendering for 150ms on slow networks

Performance Comparison

Pattern	DOM Operations	Reflows	Paint Cost	Verdict
Import full library	N/A	N/A	High due to large JS execution	[X] Bad
Import only used components	N/A	N/A	Low due to smaller JS execution	[OK] Good

Rendering Pipeline

Bundle analysis and tree shaking reduce the amount of JavaScript the browser must download, parse, and execute before rendering the page.

→Network

→Parse & Compile

→Script Execution

→Style Calculation

→Layout

⚠️ BottleneckParse & Compile stage is most expensive due to large bundles

Core Web Vital Affected

LCP

This concept affects the page load speed by reducing the JavaScript bundle size and improving initial download and parse time.

Optimization Tips

1Always import only the components you use to enable tree shaking.

2Use bundle analysis tools to identify large dependencies.

3Apply code splitting to load code on demand and reduce initial bundle size.

Performance Quiz - 3 Questions

What is the main benefit of tree shaking in a Vue project?

A Removes unused code to reduce bundle size

B Improves CSS styling performance

C Automatically caches API responses

D Increases the number of components loaded

DevTools: Network and Performance panels

How to check: Open DevTools, go to Network tab, filter by JS files to see bundle sizes; then use Performance tab to record page load and check scripting time.

What to look for: Look for large JS files blocking the main thread and long scripting times indicating heavy parsing and execution.