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Optimizing Your Frontend Performance
This document discusses various techniques for optimizing frontend performance, including: 1. Using hardware, backend, and frontend optimizations like combined and minified files, CSS sprites, browser caching headers, and content delivery networks. 2. Analyzing performance with tools like Firebug, YSlow, and Google Page Speed to identify opportunities. 3. Specific techniques like gzipping, avoiding redirects, placing scripts at the bottom, and making Ajax cacheable can improve performance.
Optimizing Your Frontend Performance
- 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 scaleyou 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
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- 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
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- 19. Google Page Speed ● Firebug extension ● CSS complexitiy
- 20. Google Page SpeedScreenshot
- 21. Make Fewer HTTPRequests ● 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 ACDN ● 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 PHP5 <?php ob_start('ob_gzhandler'); ...
- 35. Gzip In PHP5 <?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 acrossdomains ● 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 atthe Top ● Progressive display of the page ● Page appears to load faster ● W3C specifications
- 42. Put Scripts atthe 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 CSSFiles ● 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