Why does Performance Matter?
Software Engineer @Adidas
Some stats before start
Global digital population (in millions)
Active Internet U. Unique Mobile Internet U. Active Social Media U. Active Mobile Social Media U.
Number of internet users (in millions)
Asia Europe North America South America Africa Ocenia
Internet Users Population
Mobile Internet Usage
South America 31,31
Online Shopping in UK (Clothes and Shoes)
Clothes and Shoes Revenue Average revenue per user
20bn Euro 500 Euro
Number of Shoppers buy Clothes Number of Shoppers buy Shoes
What is performance?
Objective measurements of
time to load, frames per second and time to interactive
Perceived user experience of load time and runtime
number of resources are some of the features
that can impact the performance
…and continuously measuring
the actual and perceived speed of the application,
optimising and monitoring the performance
Why we bother?
It is all about retaining the user,
and increasing the revenue
Underperforming applications can annoy users,
can lead to unresponsive app state
or inaccessible inputs
that leads to lose your visitors
Case studies that show high performing sites
engage and retain users
where low performing sites had a
negative impact on business goals
Pinterest, rebuilt their pages for performance,
40% decrease in wait time,
15% increase in SEO traffic
and 15% increase in conversion rate to signup
Zalando, uplifted their revenue per session by 0.7%
with just 100msec improvement in their loading time
53% of visits to mobile sites are abandoned after 3
seconds according to research from Google's DoubleClick.
The BBC found they lost an additional 10% of users
for every additional second their site took to load
One of the key facts as importance of
the performance is improving the conversion
AliExpress reduced load time by 36%
and saw a 10.5% increase in orders and
a 27% increase in conversion for new customers.
Walmart saw up to a 2% increase in conversions
for every 1 second of improvement in load time.
Every 100msec improvement also resulted in
up to a 1% increase in revenue.
Amazon sees a 1% decrease in revenue
for every 100msec increase in load time.
User experience is another driving factor
to your performance
Time To Interactive
People are also important!
Data costs money for people on their mobile data plans
The sum of transfer size kilobytes of all resources requested by the page.
In addition to saving your users money,
fast and lightweight user experiences
can also be crucial for users in crisis.
How to improve Performance?
When you're building a modern web experience, it's
important to measure, optimise, and monitor if you're to get
fast and stay fast.
Discover performance opportunities with Lighthouse
Reduce your text-based resource sizes
by minifying them.
Also compress those files with Gzip or Brotli
Images are the heaviest resources
in a page in terms of size.
Optimise your images by reducing their size
and compressing them
Videos are faster to load than Animated GIFs
Lazy-load your images as they needed
Serve responsive image sizes
and correct dimensions depending on the device.
Mobile devices do not need bigger images!
yet it is the biggest problem that slows down your site
Push/Preload the most import resources.
Render the initial route as soon as possible.
Pre-cache remaining assets.
Lazy-load other routes and non-critical assets
into smaller chunks that can
parse and execute faster than one big file
Remove unused code from your sources,
by importing only needed part and tree-shaking
Do not use Polyfills, if you do not need them.
Serve modern code for modern browsers
"last 1 version",
"maintained node versions",
Your styles have also effects on your page load.
Your page will only render as quickly as your slowest
Extract critical CSS and load them first.
Defer loading the non-critical styles.
Continuously monitor your application to find new
• Web Performance https://developer.mozilla.org/en-US/docs/
• Why performance matters? https://developers.google.com/
• Case Studies https://wpostats.com/
• Statistics https://www.statista.com/