Project setup with create-svelte - Performance & Optimization

Performance: Project setup with create-svelte

MEDIUM IMPACT

This affects the initial page load speed and bundle size by determining which features and dependencies are included from the start.

Setting up a new Svelte project with create-svelte

Svelte

npm create svelte@latest my-app
# Choose only needed features, e.g., no TypeScript or testing if not required
npm install
npm run dev

Smaller dependency set and less code means faster bundle generation and quicker page load.

📈 Performance Gainsaves 150kb+ in bundle, reduces initial blocking time

Setting up a new Svelte project with create-svelte

Svelte

npm create svelte@latest my-app
# Select all optional features like TypeScript, ESLint, Prettier, Playwright, and testing
npm install
npm run dev

Including all optional features adds unnecessary dependencies and code, increasing bundle size and slowing initial load.

📉 Performance Costadds 200kb+ to bundle, blocks rendering longer during startup

Performance Comparison

Pattern	DOM Operations	Reflows	Paint Cost	Verdict
Full feature setup with all options	Moderate (more components)	Multiple (due to complex styles)	High (larger CSS and JS)	[X] Bad
Minimal feature setup with only essentials	Low (fewer components)	Single or none	Low (smaller CSS and JS)	[OK] Good

Rendering Pipeline

The project setup determines which scripts and styles are included in the initial bundle. Larger bundles increase download and parse time, delaying Style Calculation and Layout stages.

→Network

→Style Calculation

→Layout

→Paint

⚠️ BottleneckNetwork and Style Calculation due to larger bundle and CSS

Core Web Vital Affected

LCP

This affects the initial page load speed and bundle size by determining which features and dependencies are included from the start.

Optimization Tips

1Choose only essential features during create-svelte setup to keep bundles small.

2Avoid adding unnecessary dependencies that increase load time.

3Use DevTools Network and Performance tabs to monitor bundle size and load speed.

Performance Quiz - 3 Questions

How does selecting all optional features during create-svelte setup affect performance?

A It decreases bundle size and speeds up load

B It has no effect on performance

C It increases bundle size and slows initial page load

D It only affects runtime memory, not load speed

DevTools: Network and Performance

How to check: Open DevTools, go to Network tab, reload page and check bundle size and load time. Then use Performance tab to record page load and see scripting and rendering times.

What to look for: Look for smaller JS and CSS files and shorter scripting and rendering blocks indicating faster load and paint.