20 tips for website performance

20 Tips
for tweaking your website’s performance
Slides: https://nven.tv/web-perf-pdf

22
inventive.io
@InventiveGroup
facebook.com/InventiveGroup
Andrew Siemer
Founder & CEO
(866) 500-2706
hello@inventive.io
@asiemer
http://www.linkedin.com/in/AndrewSiemer

Extreme Example
Performance should be in mind from the start!
(866) 500-2706 - inventive.io - hello@inventive.io | Web Applications & Sites, Mobile Apps, Modernization

IMPROVING LIVES WITH TECHNOLOGY
Aggie Muster - From Concept to Production in 3 weeks
4
(1) Concept
(2) Wireframe
(3) Prototype
Delivered (4)

IMPROVING LIVES WITH TECHNOLOGY
Aggie Muster - Site for live streaming and real-time communication
5
● 200,000 users could log on - targeted 400k users
● Prototyped, built, load tested, & deployed in 3 weeks
● Load tested 50,000 concurrent write operations
○ During 4 hour test
○ Processed 4 million messages
○ 2,500 requests per second
○ 100 servers TESTED BEYOND REQUIREMENTS
● During Muster we saw 50,000 unique visitors
○ 14,000 registrations
○ 15,000 HERE messages
○ 1000 reﬂections
○ At peak around 7pm: 27,516 active users
■ 800 requests per second across
35 servers
○ Average request duration for reads <10ms
● Hosting costs
○ Day of event: $565
○ Outside of the event: $60-$80/month

What is Performance?
Now let's understand the problem

What is Performance?
● Page load speed
39% leave sites that render slowly
● Time to first render
74% leave if the site doesn’t load on the phone in 5 seconds
● Time to interactive (useable)
52% cite that quick page load is important to site loyalty
● Perceived performance
16% satisfaction decrease for 1 second page speed delay

20 tips for website performance

Without performance
● Not an enjoyable experience
A 0.4 second lag time results in decrease of 0.44% traffic
● Users won’t stick around
A 1 second delay in page load time means 11% decline in page views
● Google will demote you
0.5 second in each search page generation causes traffic to drop by 20%

● Now indexes your mobile site
experience by default
● Should provide a 100% identical
experience as desktop
● Render speed of mobile should
be blazing fast and lightweight
● Accessibility friendly
https://search.google.com/test/mobile-friendly
https://nven.tv/web-perf-google-mobile-ﬁrst

Test with your users in mind
Look at your Google analytics to understand who your users are
- 53% of mobile site visits are abandoned if pages take longer than 3 seconds to load

Device performance varies
Sometimes significantly!
- 75% of users won’t return to a webpage if it takes more than 4 seconds to load

http://buildingadevicelab.com/

Device Considerations
● Processor speed
● Memory available
● Wifi vs cellular connectivity
● Signal strength

Not all bytes are equal!
100kb of JS “weighs” more than 100kb of image.

Performance Issues
What to look for...

Highlights
Quick Fixes
1. HTTP Requests
○ Reduce DNS lookups
○ Minimize redirects
○ Remove query strings from static
resources
○ Avoid bad requests
2. Specify a character set
3. Fonts
○ System Font Stack
○ Font subsetting
4. CSS at the top, JS at the bottom
5. Images
○ Optimize Images
○ Specify image dimensions
○ Image sprites
○ Lazy load below the fold
Other Fixes
1. Hosting
○ HTTP/2
2. Expires header
3. GZIP compression
4. Use a CDN
5. Cached 302 redirects
6. Tree shaking / UnCSS
7. Code splitting
8. Minify your code

Quick Fixes
Easy fixes that are directly under
your control

Quick Fixes
● HTTP Requests
● Character sets
● Fonts
● External resources
● Images

HTTP Requests
● Reduce DNS lookups
● Minimize redirects
● Remove query strings from
static resources
● Avoid bad requests

HTTP Requests
static resources
How a 301 redirect works

HTTP Requests
static resources
http://deadlinkchecker.com

Character Sets
● Specify the character set to
make the browser’s job easier!
● Must be in the first 1024 bytes
of the document!
<html …>
<head …>
<meta charset="utf-8">
https://nven.tv/web-perf-character-set

Fonts & Flash of unstyled content
● Consider not loading a font! Or
use “System Font Stack”
● Use CDN for font hosting
● Use WOFF2 format
● Us subset fonts including only needed characters
https://everythingfonts.com/subsetter

External Resources
● Images covered below
● CSS at the top
● JS at the bottom
● Inline critical CSS for above the
fold content
● Asynchronously load
non-critical CSS
○ Prohibits progressive
rendering of critical styles
○ Avoid redraws
○ Improves web standard
compliance according to
W3

Images
● Optimize Images
● Specify image dimensions
● Image sprites
● Lazy load below the fold
https://css-tricks.com/essential-image-optimization/

Images
● Optimize Images
● Image sprites

Images
● Optimize Images
● Image sprites
● HTTP/1.1 likes one request due
to queuing limitation
● HTTP/2 likes little requests due
to multiplexing
● A sprite with many images in
one file may compress better
that individual images
● If all images in a sprite are used
on one page, that may be a
better option
https://css-tricks.com/css-sprites/

Images
● Optimize Images
● Image sprites
https://css-tricks.com/the-complete-guide-to-lazy-loading-images/

Other Fixes
These fixes may require a team
effort

Other Fixes
● Hosting
● Expires header
● GZIP compression
● Use a CDN
● Cached 302 redirects
● Tree shaking & UnCSS
● Code splitting
● Minify your code

Hosting
● HTTP2
● Servers near consumers
● Globally available - short hops
● Heavily cached static content
● Scalable infrastructure for
dynamic content
● If monolithic server, be sure
they are performant
● Limit noisy neighbors on shared
hosting

Hosting
● HTTP/2
○ Faster
○ Stream of binary
frames
○ More Secure
- Requires server configuration
https://nven.tv/web-perf-http2

Expires Header
● Allows you to leverage browser
caching
● Instructs browser to use local
copy of an already downloaded
file
● Reduces number of HTTP
requests to load page

GZIP Compression
● Compresses the content on the
server
● Less for the browser to
download
● Browser then decompresses
the content for display

CDN for Static Assets
● Get website assets as close to
your user as possible
● Offloads web traffic from your
host
● Caching on a highly performant
edge network
● Provides a form of redundancy
● Helps with scale

Cached 302 Redirects
● Redirects add latency to a
request
● Redirects delay page load time
● Remove redirects if possible
● Cache them if you can’t remove
them

Tree Shaking & UnCSS
● Remove dead code paths
○ From Javascript
○ From CSS
- Best when part of continuous integration

Code Splitting
● Send small specific bundles of code
● Minimizes the size of a request
● Utilize dynamic importing

Minify Your Code
● Removes whitespace
● Shortens variable names
● Shortens function names

Monitoring
Performance must be monitored over time

One-time Audit
Isn’t good enough!

Monitoring Tools
● SpeedCurve
● Request Map Generator
● Size Limit
● Google Lighthouse
https://speedcurve.com

Monitoring Tools
● SpeedCurve
● Size Limit
https://nven.tv/web-perf-tamu-rm

Monitoring Tools
● SpeedCurve
● Size Limit
https://github.com/ai/size-limit

Monitoring Tools
● SpeedCurve
● Size Limit

Perceived Performance
Sometimes you can pretend to be performant!

Animations
Load and calculate in the
background while showing an
animation

Extras
Some additional considerations

Extras
1. Performance Budget
○ Be 20% faster than your main competitor
2. Performance = Ethics & Accessibility
3. Follow the specialists
○ Performance is an industry
○ Changes over time

Resources Used
● https://nven.tv/web-perf-moz-15
● https://nven.tv/web-perf-35-tips
● https://nven.tv/web-perf-improve-conversion
● https://nven.tv/web-perf-google-mobile-first

An inventive company
solving big problems
with proven solutions
MORE THAN DIGITAL TRANSFORMATION
IMPROVING LIVES WITH TECHNOLOGY60
QUESTIONS?

An inventive company
solving big problems
with proven solutions
MORE THAN DIGITAL TRANSFORMATION
IMPROVING LIVES WITH TECHNOLOGY61
QUESTIONS?

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