Create Next App setup in NextJS - Performance & Optimization

Performance: Create Next App setup

MEDIUM IMPACT

This affects the initial page load speed and bundle size by determining how the app is scaffolded and dependencies are included.

Setting up a new Next.js project for fast initial load

NextJS

npx create-next-app@latest my-app --use-npm
# Creates a minimal starter with only essential dependencies

Minimal setup avoids extra dependencies and large example code, reducing bundle size and speeding up first paint.

📈 Performance Gainsaves 300kb+ in bundle, reduces blocking time by 200ms

Setting up a new Next.js project for fast initial load

NextJS

npx create-next-app@latest my-app --use-npm --example with-redux-toolkit
# This installs a large example with many dependencies not needed initially

Including large example templates adds unnecessary dependencies and code, increasing bundle size and slowing initial load.

📉 Performance Costadds 300kb+ to initial bundle, blocks rendering for 200-300ms longer

Performance Comparison

Pattern	DOM Operations	Reflows	Paint Cost	Verdict
Minimal Create Next App setup	Minimal DOM nodes	1 reflow on initial load	Low paint cost	[OK] Good
Create Next App with large example template	More DOM nodes from example	Multiple reflows due to heavy scripts	Higher paint cost	[X] Bad

Rendering Pipeline

The Create Next App setup determines the initial JavaScript and CSS loaded, affecting style calculation, layout, and paint stages during first load.

→Style Calculation

→Layout

→Paint

→Script Evaluation

⚠️ BottleneckScript Evaluation due to large bundles from unnecessary dependencies

Core Web Vital Affected

LCP

This affects the initial page load speed and bundle size by determining how the app is scaffolded and dependencies are included.

Optimization Tips

1Start with the minimal Create Next App template to keep bundles small.

2Avoid adding large example templates that include unnecessary dependencies.

3Use lazy loading and code splitting to reduce initial script evaluation time.

Performance Quiz - 3 Questions

What is a performance downside of using a large example template when creating a Next.js app?

A It improves caching automatically

B It increases the initial bundle size and delays page load

C It reduces the number of DOM nodes

D It decreases script evaluation time

DevTools: Performance

How to check: Open Chrome DevTools > Performance tab > Record page load > Look at Main thread for script evaluation and rendering times

What to look for: Long scripting tasks and delayed first contentful paint indicate heavy initial bundles from setup