Vue CLI and Vite setup - Performance & Optimization

Performance: Vue CLI and Vite setup

MEDIUM IMPACT

This affects how fast the development server starts and how quickly the app loads in the browser.

Setting up a Vue project for development with fast reload and build times

Vue

npm create vite@latest my-app -- --template vue
cd my-app
npm run dev

Vite serves source files over native ES modules and only bundles on build, enabling near-instant startup and fast hot module replacement.

📈 Performance Gainstartup under 300ms, reloads only changed modules, reducing blocking and improving LCP

Setting up a Vue project for development with fast reload and build times

Vue

vue create my-app
cd my-app
npm run serve

Vue CLI uses webpack which bundles the entire app before serving, causing slower startup and reload times.

📉 Performance Costblocks rendering for 1-3 seconds on startup, triggers full page reload on changes

Performance Comparison

Pattern	DOM Operations	Reflows	Paint Cost	Verdict
Vue CLI setup	N/A (build tool)	N/A	Higher initial paint delay due to bundled scripts	[X] Bad
Vite setup	N/A (build tool)	N/A	Lower initial paint delay with native modules and fast reload	[OK] Good

Rendering Pipeline

The setup affects the critical rendering path by controlling how fast the browser receives and processes JavaScript modules. Vue CLI bundles delay initial script loading, while Vite streams modules natively.

→Network

→Script Parsing

→Style Calculation

→Layout

→Paint

⚠️ BottleneckNetwork and Script Parsing due to large bundled files in Vue CLI

Core Web Vital Affected

LCP

This affects how fast the development server starts and how quickly the app loads in the browser.

Optimization Tips

1Use Vite for faster development server startup and reload times.

2Avoid full bundling during development to reduce blocking and improve LCP.

3Leverage native ES modules to speed up script parsing and module updates.

Performance Quiz - 3 Questions

Which setup generally provides faster development server startup for Vue projects?

A Vue CLI using webpack bundling

B Both have the same startup speed

C Vite using native ES modules

D Neither affects startup speed

DevTools: Performance

How to check: Open DevTools, go to Performance tab, record page load, and compare script evaluation and time to first contentful paint.

What to look for: Look for shorter scripting and loading times with Vite compared to Vue CLI, indicating faster LCP.

Practice

1. What is the main purpose of Vue CLI and Vite in Vue development?

easy

A. To quickly create and manage Vue projects with build tools

B. To write Vue components without JavaScript

C. To replace Vue Router for navigation

D. To convert Vue code into plain HTML only

Solution

1. Step 1: Understand Vue CLI and Vite roles

   Both Vue CLI and Vite are tools to start Vue projects easily and provide build and development features.

2. Step 2: Identify their main purpose

   They help set up projects quickly with live reload and bundling, not replacing Vue Router or removing JavaScript.

3. Final Answer:

   To quickly create and manage Vue projects with build tools -> Option A

4. Quick Check:

   Vue CLI and Vite purpose = C [OK]

Hint: Think: tools to start and build Vue apps fast [OK]

Common Mistakes:

• Confusing Vue CLI with Vue Router
• Thinking Vite removes JavaScript
• Believing these tools only output HTML

2. Which command correctly creates a new Vue project using Vite?

easy

A. vue create my-vue-app

B. npm create vite@latest my-vue-app -- --template vue

C. npm install vite vue

D. vite new project vue

Solution

1. Step 1: Recall Vite project creation syntax

   The official way to create a Vue project with Vite is using npm create vite@latest with the --template vue flag.

2. Step 2: Compare options

   npm create vite@latest my-vue-app -- --template vue matches this syntax. vue create my-vue-app is Vue CLI syntax. Options C and D are incorrect commands.

3. Final Answer:

   npm create vite@latest my-vue-app -- --template vue -> Option B

4. Quick Check:

   Vite create command = B [OK]

Hint: Vite uses 'npm create vite@latest' with template flag [OK]

Common Mistakes:

• Using 'vue create' for Vite projects
• Trying to install Vite and Vue separately to create project
• Using invalid commands like 'vite new'

3. Given this command run in a terminal: vue create my-app, what will happen?

medium

A. It installs Vue globally on the system

B. It instantly creates a Vue project without prompts

C. It starts an interactive setup to create a Vue project

D. It runs the Vue development server immediately

Solution

1. Step 1: Understand 'vue create' command behavior

   The vue create command from Vue CLI launches an interactive prompt to select project options.

2. Step 2: Analyze other options

   It does not create instantly without prompts, nor does it install Vue globally or start the server immediately.

3. Final Answer:

   It starts an interactive setup to create a Vue project -> Option C

4. Quick Check:

   vue create = interactive setup [OK]

Hint: vue create prompts you to choose project options [OK]

Common Mistakes:

• Thinking it creates project instantly
• Confusing with npm install commands
• Expecting it to start the server automatically

4. You run npm run dev in a Vite project but get an error saying 'command not found'. What is the likely cause?

medium

A. You forgot to run npm install to install dependencies

B. You need to use vue serve instead

C. The dev script is only for Vue CLI projects

D. You must run vite build before npm run dev

Solution

1. Step 1: Understand npm scripts and dependencies

   The npm run dev command runs the dev server script defined in package.json. If dependencies are missing, the script may fail.

2. Step 2: Identify cause of 'command not found'

   Not running npm install means dependencies like Vite are missing, causing the error.

3. Final Answer:

   You forgot to run npm install to install dependencies -> Option A

4. Quick Check:

   Missing dependencies cause 'command not found' [OK]

Hint: Always run npm install before npm run dev [OK]

Common Mistakes:

• Using Vue CLI commands in Vite projects
• Trying to build before dev without install
• Assuming dev script is only for Vue CLI

5. You want to switch a Vue project from Vue CLI to Vite. Which step is essential to start this migration?

hard

A. Just change the start script in package.json to use Vite

B. Run vue upgrade vite to convert automatically

C. Replace vue.config.js with vite.config.js without changing files

D. Create a new Vite project and move your source files into it

Solution

1. Step 1: Understand migration approach

   Vue CLI and Vite have different setups. The safest way is to create a new Vite project and move your source code there.

2. Step 2: Evaluate other options

   There is no automatic vue upgrade vite command. Simply replacing config files or scripts won't work due to different build systems.

3. Final Answer:

   Create a new Vite project and move your source files into it -> Option D

4. Quick Check:

   Migration starts with new Vite project + source move [OK]

Hint: Start fresh Vite project, then copy your code [OK]

Common Mistakes:

• Expecting automatic conversion commands
• Only changing config files without new setup
• Assuming changing scripts is enough