There's so many ways to speed up your site. Don't you wish every web performance tip was in one place? That's what I thought too, so I put them all in one place: this post.
Use this guide as a reference.
Table Of Contents
HTML
✨ Minify HTML
☄️ Order your styles and scripts for pagespeed
⚡️ Eliminate render-blocking resources
🌟 Minimize layout thrashing
🎉 Prioritize resources
✨ Preload critical assets to improve loading speed
💥 Establish network connections early
⚡️ Prefetch resources
🌟 Implement adaptive serving
CSS
⭐️ Minify CSS
✨ Remove unused CSS
💥 Defer non-critical CSS
⚡️ Minimize CSS requests by combining external CSS
🚀 Optimize CSS background images with media queries
⭐️ Avoid CSS inside the body tag
☄️ Inline critical CSS
✨ Avoid expensive styles
💫 Optimize CSS length
Images
✨ Choose the right image format
💫 Choose the correct level of compression
⭐️ Use Imagemin to compress images
💥 Defer offscreen images
⚡️ Properly size images
✨ Replace animated gifs with video
🎉 Serve responsive images
⚡️ Serve images with correct dimensions
🌟 Use WebP images
⚡️ Use AVIF images
🎊 Use image CDNs to optimize images
✨ Use lazy-loading
🚀 Lazy-loading video
⚡️ Use lazysizes to lazy-load images
⭐️ Compress JPEG images
🔥 Optimize PNG images
✨ Optimize SVG vector files
Fonts
💫 Avoid invisible text during font loading
💥 Use preconnect to load fonts faster
⚡️ Optimize Webfont loading and rendering
☄️ Reduce Webfont Size
✨ Keep Webfont size under 300kb
JavaScript
💫 Apply the PRPL pattern
⭐️ Limit the size of NPM dependencies
⚡️ Use code splitting
🌟 Combine external JavaScript
💥 Remove unused code
🎉 Use tree-shaking in Webpack
✨ Minify JavaScript
💫 Serve modern code to modern browsers
🌟 See how CommonJS makes your bundles larger
⚡️ Defer loading JavaScript
⭐️ Prefer Vanilla JavaScript🎊
💡 Use service workers to cache data
🎊 Use web workers
💥 Write optimized code for V8
🎉 Compile your JavaScript to faster JavaScript with Prepack
✨ Compile your JavaScript to faster JavaScript with Closure Compiler
Server
☀️ Use HTTPS
☄️ Keep the size of cookies low as possible
🔥 Avoid bad requests
💫 Set HTTP cache headers
⭐️ Enable gzip and brotli compression
⚡️ Self-host your static asssets
🌟 Enable OCSP stapling
💥 Adopt IPv6
💡 Serve assets over HTTP/2
🎉 Implement HPACK compression
✨ Set proper security headers
Testing Tools
💫 Measure site speed with Pingdom
🌟 Measure site speed with WebPageTest
🎊 Measure performance with the RAIL model
⚡️ Configure Webpack performance hints
⭐️ Use bundlesize
💥 Measure JavaScript execution time
🎉 Use lighthouse-ci
☄️ Use Lighthouse Bot to set a performance budget
☀️ Test on remote real devices
🔥 Use Sitespeed
✨ Use Calibre
💫 Use SpeedCurve
🎊 Use k6
⚡️ Use SpeedTracker
Frameworks
⭐️ Use an ahead of time compiler
💥 Improve Angular performance
☀️ Debug React perfomance
🔥 Eliminate common React issues
✨ Make components connection aware
💫 Implement adaptive serving
🎉 Serve Adaptive Components Using the Network Information API
Discussion
Nice! Lots of goodies in here and this is a great checklist.
The CSS section should have something like:
“Inline Your Critical CSS” which reduces the number of requests and helps with render blocking.
Done!
Nice thanks! I didn’t know about that Library.
This deserves a github repository .
like Awesome web performance..
Just dope?
What can I say, it's just what I needed to do that 😆
Yo that's dope.
Just dope?
THIS IS A GODSEND!!!!!!!!
How long did this take you to prepare?
I would add this one: Serve Modern Code to Modern Browsers for Faster Page Loads web.dev/serve-modern-code-to-moder...
That's already in the article :-)
Sorry I completely missed it! 🙃
You could add a
critical-pathsections, there may be some tools / techniques here for you to add to yours:github.com/addyosmani/critical-pat...
:)
The article already links to Addy Osmani's Critical library.
Impressive list, very complete!
Excellent list. Please add JMeter under testing tools.
Nice!!! Thanks
Thanks a ton for collating them.
That's just awesome. 👏💯
Also a follow up: add AVIF format to images
reachlightspeed.com/blog/using-the...
done!
Thanks I can create my own checklist now
This is very useful list
The suggestion to combine CSS and other types of files, is that still true in the age of http2 and the probably soon coming of http3?
HTTP requests are still expensive. I personally make an exception to bundling for very large JS files (which you should avoid in the first place). In the past, with benchmarking, I found that bundling small files = performance gains but bundling large JS files = more execution time.
There are limitations to bundling due to file size, but also, HTTP/2 adoption isn't universal. You may be interested in this other article about bundling.
There is definitely a way to bundle correctly. For example, if you generate different bundles on every build, you have to consider that the user never gets to cache your assets.
content-visibility - limited browser support right now.
web.dev/content-visibility/
caniuse.com/css-content-visibility