1. PHPNW09
Thomas Weinert
Optimizing Your Frontend Performance

2. About Me
● Application Developer
– PHP
– XSLT/XPath
– (some) Javascript
● papaya CMS
– PHP based Content Management System
– uses XSLT for Templates

3. How to scale you webpage?
● Hardware
● Backend
● Frontend

4. Hardware
● More hardware
● Better hardware
● Moores Law
– Transistors doubling every 18 months
– Transistors != Performance
● Distributed systems are complex
● Think about environment

5. Backend
● External data sources are slow
– SQL
– Files
– Network
● Locking is slower
● Memory is faster
– but less secure

6. Mini/Micro Optimisations
● Myths
– echo vs. print
– ' vs. "
● Objects vs. functions vs. linear source
● Template systems

7. Mini/Micro Optimisations
DON'T DO IT

8. Yahoo!
● Yahoo!'s Exceptional Performance team
– Yahoo!'s Exceptional Performance team
evangelizes best practices for improving web
performance. They conduct research, build tools,
write articles and blogs, and speak at conferences.
Their best practices center around the rules for high
performance web sites.
– http://developer.yahoo.com/performance/

9. Results
● 80% of the end-user response time is spent on
the front-end.

10. Firebug
● Firefox extension
● Analyze and manipulate
– requests, page structure, CSS
● Javascript debugger

11. Firebug Requests

12. Firebug Request II

13. HTTPFox
● Firefox Extension
● Log of all HTTP requests
– Redirects
– Cached requests

14. YSlow
● Why (is your web page) slow
● Set of rules
● Firebug extension

15. Yslow: Performance View

16. Yslow: Stats

17. Yslow: Components

18. Yslow: Tools

19. Google Page Speed
● Firebug extension
● CSS complexitiy

20. Google Page Speed Screenshot

21. Make Fewer HTTP Requests
● Combined files
– CSS
– JavaScript
● CSS sprites

22. Combined files
● Release process
● CSS
– Consider URLs
● JavaScript
– Minify
– Obfuscate

23. CSS Sprites
● Elements with fixed size
● Background image
● Disable repeat
● Negative positions

24. CSS Icons
● Raster of icons
● No repeat
● Fixed size
<div> or <span>

25. CSS Backgrounds
● Gradient
● Repeat in one
direction

26. Minify Javascript
● Most JS libraries provide a minified version
● YUI Compressor:
http://developer.yahoo.com/yui/compressor/
– JS and CSS
● Packer
– Webpage, .Net, Perl, PHP
– http://dean.edwards.name/packer/

27. #2 Use A CDN
● Content Delivery Network
– Akamai Technologies
– Mirror Image Internet
– Limelight Networks
● Bring the content to your users
– Geographic distance
– Physics is still here
● Only for large sites
● Dynamic content is complex

28. Headers
● Expires
● Cache-Control
– Session-Management
● 304 Not Modified

29. Expires
● Apache mod_expire
●
● <IfModule mod_expires.c>
● ExpiresDefault "access plus 1 month"
● ExpiresActive on
● </IfModule>

30. Cache-Control
● None
– no caching
– default for sessions
● Private
– cacheable in browser cache
● Public
– cacheable in browser cache and proxies

31. 304 Not Modified
● Send Etag and Modfication date
– Etag: "some hash"
– Last-Modified: Thu, 12 Sep 2008 11:00:00 GMT
● Request headers
– If-Modified-Since: Tue, 12 Sep 2008 11:00:00 GMT
– If-None-Match: "some hash"
● Response headers
– HTTP/1.1 304 Not Modified

32. Gzip Components
● Gzip != Zip
– only compression
– no packaging
– tar.gz
● Good browser support
– Accept-Encoding: gzip, deflate
– Content-Encoding: gzip
–

33. Gzip in Apache
● mod_gzip
● mod_deflate
– filter chain, works on dynamic content, too
●
– http://httpd.apache.org/docs/2.2/mod/mod_deflate.html

34. Gzip In PHP 5
<?php
ob_start('ob_gzhandler');
...

35. Gzip In PHP 5
<?php
if (function_exists('ob_gzhandler')) {
ob_start('ob_gzhandler');
}
...

36. Gzip Problems
● Not supported:
– Transfer-Encoding: chunked
– HTTP 1.0 client (old Squids)

37. Configure ETags
● Browser still asks webserver
● Server specific
– CDN
– Load balancer with multiple servers
● Apache
– FileETag none
● IIS
– http://support.microsoft.com/?id=922733

38. Split requests across domains
● HTTP 1.1 suggests 2 parallel requests per
domain
● Separate content by function
– www.domain.tld
– themes.domain.tld
– usercontent.domain.tld (security)
● Optimisation tools change the option
● Consider cookie domains

39. Reduce DNS Lookups
● DNS maps host names to ips
● Needs time
– 20-120 milliseconds
● Cached in browser

40. Avoid Redirects
● Obviously addition requests
● Only cached with explicit headers
● http://www.domain.tld
– → http://www.domain.tld/

41. Put Stylesheets at the Top
● Progressive display of the page
● Page appears to load faster
● W3C specifications

42. Put Scripts at the Bottom
● Scripts block parallel downloads
– defer attribute in MSIE
● onload() event
– used by most libraries
● Problem: document.write()
– Counter
– Banners

43. Avoid CSS Expressions
● MSIE from version 5
– cross browser experience
● JavaScript inside CSS
● Evaluated
– page render
– resize
– scrolling
– mouse movements (hover)

44. JavaScript And CSS Files
● Do not embed JS/CSS in your pages
– No <script>...</script>
– No <style>...</style>
● Seperate caching headers
● Revision parameter (style.css?rev=1234)
– Get parameter
– Unique URL for browser
– Possibly in path/filename

45. Remove Duplicate Scripts
● Team size
● Standard scripts
– XMLRPC, JQuery, Prototype
● Script module for your template system
● $templatesystem->addScript('foo.js');

46. Make Ajax Cacheable
● Often AJAX applications avoid caching
– http://some.domain.tld/ajax.file?t=randomvalue
● A lot of requests
● Use more static URLs

47. References
● Slides: http://www.a-basketful-of-papayas.net/
● Yahoo Performance Team
– http://developer.yahoo.com/performance/
● Google Page Speed
– http://code.google.com/intl/en-UK/speed/page-speed/
● Apache GZIP
– http://httpd.apache.org/docs/2.2/mod/mod_deflate.html
● No Etag in IIS
– http://support.microsoft.com/?id=922733