Text compression & Code splitting & Modern image formats - Performance optimization

I tried the following to optimize my side project performance:

1. text compression
2. code splitting
3. modern image formats.

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Profiler

The app I built used Vite with pnpm. Modern web build tools automatically optimize web performance by default in the build process. So we can pnpm run build then pnpm dlx serve dist. Then use Lighthouse of Chrome DevTools as a guide to address each bottleneck it lists.

Enable text compression

It affects FCP and LCP.

The first thing that Lighthouse suggests is compressing text using algorithms like br or gzip.

The common practice is to add Accept-Encoding: gzip whenever making web requests. Since the app I am building serves the resource locally, I installed the vite-plugin-compress to compress the files.

Step 1: install vite-plugin-compress
Step 2: configure the vite.config.js file, and add the plugin and some parameters. As Google Developers suggests, it should use br(brotliCompress) over gzip as much as possible.

For example

viteCompression({
      verbose: true,
      disable: false,
      algorithm: 'brotliCompress',
      ext: '.br',
    }),

Step 3: run pnpm run build to compress

It successfully compressed .js and .css files.

Logs:

✨ [vite-plugin-compression]:algorithm=brotliCompress - compressed file successfully.

Vite would compress the file by default using .gzip, but brotliCompress can do better, compression during the build process:

Vite with gzip

vite v5.4.10 building for production...
✓ 654 modules transformed.

index-B9QUW17e.css 8.60 kB │ gzip: 2.33 kB
PauseMenu-DjZ95K-6.js 1.77 kB │ gzip: 0.62 kB
index-ohAKp9W9.js 1,688.05 kB │ gzip: 454.20 kB

Vite-plugin-compression with br

✨ [vite-plugin-compression]:algorithm=brotliCompress - compressed file successfully:
PauseMenu-DjZ95K-6.js.br 1.73kb / brotliCompress: 0.51kb
index-B9QUW17e.css.br 8.40kb / brotliCompress: 1.97kb
index-ohAKp9W9.js.br 1648.49kb / brotliCompress: 345.30kb

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Reducing unused JavaScript

It affects FCP and LCP.

Use the Coverage Tab in Google DevTools to see the scripts that have unused bytes over 20kbs.

Since I am using Vite with React, code splitting is the first thing about reducing unused JavaScript.

In React, and lazy() can help with that.

1. Use to wrap the whole App and provide a fallback UI, like
   Loading
   , this provides a fallback UI when the app is loading.
2. Use lazy() to wrap the components which not used on the initial page. For example, for games, when users press down the Esc key, a menu that you can wrap up pops up.

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Serve images with modern formats

Chrome Developers suggests serving images in AVIF or WebP format. I chose WebP because it has more support across browsers.

The latest versions of Chrome, Firefox, Safari, Edge, and Opera support WebP, while AVIF support is more limited.

You can check WebP image format support info at Can I use.

You can install the cwebp library at WebP and use the command cwebp -q 50 images/flower1.jpg -o images/flower1.webp to convert .png to .webp.

This command converts, at a quality of 50 (0 is the worst; 100 is the best), the images/flower1.jpg file and saves it as images/flower1.webp.

The compression result is quite impressive. One of the files is reduced in size from 3.5 MB to 178kb. Even the low information intensity ones give 4x compression.

We can even write a simple .bat script to automatically convert all the .png images under the target folder into .webp images.

viteCompression({
      verbose: true,
      disable: false,
      algorithm: 'brotliCompress',
      ext: '.br',
    }),

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Reference

• Remove unused JavaScript
• View used and unused CSS with the Coverage tab.
• Serve images in modern formats.
• Creating WebP Images with the Command Line
• Precompiled Utilities
• WebP image format - Can I Use
• Largest Contentful Paint (LCP)
• First Contentful Paint (FCP)

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