1.
Caching for the Mobile Web and
Macklemore's Thrift Shop
by @rubikzube

2.
Sometimes I make poor decisions

3.
The rest of the time
● I work on shutterstock.mobi
● Eventually needs to handle 100k
visits per day around the world
● Uses a handful of web servers
● That means serious caching

4.
Caching means better performance
for users and servers
1. Make fewer requests
2. Fetch smaller resources
3. Travel shorter distances
4. Use generic pages that are cacheable
Don’t kill the servers
Do serve fast pages

5.
Start by hunting for easy wins
● Use yslow and pagespeed to find ways to make fewer
requests and to fetch smaller resources
● Try to score in the high 80s - low 90s
● Minifying, concatenating, and gzipping is only the
first step
I’m, I’m hunting,
looking for a come up,
this is f*cking awesome

6.
HTTP basics are important too
● HTTP is a core protocol of the internet
● HTTP headers determine how content will be cached
on the browser AND along the network
● If HTTP headers are set properly the browser will
travel shorter distances
Imma take your
grandpa’s style

7.
Caching involves more than
a browser and a server
Reverse
Proxies
Web
Servers
Wireless
Towers
Optional
CDNs
Internet
Routers
Mobile
Device w/
Radio
Web
Browser
billions millions 100’s 100k’s a few handfula few
Peep game, come take a look
through my telescope

8.
If headers are set correctly,
the network serves the pages
This isn’t a beer or basketball
Less hops is better
Reverse
Proxies
Web
Servers
Wireless
Towers
Optional
CDNs
Internet
Routers
Mobile
Device w/
Radio
Web
Browser
billions millions 100’s 100k’s a few handfula few

9.
A brief example
● Cache-Control: public, max-age=31536000
● Date: Tue, 17 Sep 2013 01:59:24 GMT
● Expires: Wed, 17 Sep 2014 01:59:24 GMT
● Server: nginx
● ETag: "151472-1379361363000"
Savin' my money and I'm hella
happy that's a bargain, b*tch

10.
Keep pages generic where possible
● Separate user-specific content from public pages at
the request level to make pages generic and
cacheable
Dressed in all pink
except my gator shoes,
those are green

11.
Generic
User-Specific

12.
The overall effect
Generic pages loaded from the network.
User-specific content follows from the
web server via AJAX.
Reverse
Proxies
Web
Servers
Wireless
Towers
Optional
CDNs
Internet
Routers
Mobile
Device w/
Radio
Web
Browser
billions millions 100’s 100k’s a few handfula few

13.
● Any request caches generic pages in the network,
creating a pull effect
● The more users there are, the faster the site appears
to respond
● For layering in user-specific content via AJAX
○ Use different domains
○ Use the same domain and scope user-specific content (and
cookies) to a subdirectory
More generic pages means more caching

14.
Don’t send cookies with generic pages.
EVER.
● Sending cookies with generic pages signals that the
response is not generic and should not be cached
Having the same one as six other people
in this club is a hella don’t

15.
Everyone go visit TMZ right now
Raise your hand if you can identify
why it’s slow in this diagram
Reverse
Proxies
Web
Servers
Wireless
Towers
Optional
CDNs
Internet
Routers
Mobile
Device w/
Radio
Web
Browser
billions millions 100’s 100k’s a few handfula few

16.
If the first page load is slow in the the forest,
and no one is around
● On first page load, there are too many variations in
mobile network connectivity to perceive whether the
site itself is slow
● I submit don’t optimize the first page load
● I submit the most important page load is the second
What you know about rockin' a wolf on your noggin?
What you knowin' about wearin' a fur fox skin?

17.
Optimize for the second load
● Serve all JS/CSS/Icons for the site on every page with a
year-long cache expiry
● First Load: 297.3K 16 requests
● Homepage: 7.7K 1 request
● Login: 5.4K 1 request
● Search: 28.0K 1 request + images
As for performance impact:
Browsers get better all the time,
the network doesn’t

18.
Questions?
Special shout out to @ShutterTech!
Keepin’ me honest since 2011