Frontend Caching - The "new" frontier


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You have done all the caching tricks in the book on the server side: memcache, apc, database cache and so on and squeezed every millisecond out of it, now your site is as fast as it will ever get. Well guess again !

Too often people forget that what you are effectively caching and creating with those technologies is the HTML part of the user response time, now if they are done correctly then HTML is 10 - 20% of your users response time, so there is room for a whole lot of improvements on those other 80 - 90%.

You will be taken through a couple of important steps to achieve this, such as how to optimize your JavaScript, CSS, Images, Cookies and a whole sleeve of other things that make frontend caching the magical place that it is.

After having attended this talk you will not only have learned to make your sites faster for your long term users but also people coming for the first time as well as people on slower connections.

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  • The user’s perception is more relevant than actual unload-to-onload response time. Definition of "user onload" is undefined or varies from one web page to the next.
  • User needs to download all components Coming for the first time Force refresh of the site Browser automagically cleared the cache based on settings
  • User needs to download all components Coming for the first time Force refresh of the site Browser automagically cleared the cache based on settings
  • Yahoo ran the experiment. Ran against an empty page
  • Older IE: 6 overall, 2 per host Older FF had 24 as overall and 8 per host Newer FF: 30 overall, 15 per host
  • Many host names = more DNS lookups, adds delay Consider the effects of CPU thrashing for the client Lookup times vary across ISPs and geographic locations
  • dynamically combine and cache Combine and minimize before a release
  • Don't use HTMTL attributes to scale Favicon – keep it around, keep it small
  • Frontend Caching - The "new" frontier

    1. 1. Frontend Caching The “new” frontier ZendCon – San Jose, October 2009
    2. 2. Head of R&D at echolibre , pear extraordinaire, author and from Iceland Head of R&D at echolibre , pear extraordinaire, published author and an Icelander Who is Helgi ? Head of R&D at echolibre , pear extraordinaire, author and from Iceland
    3. 8. 80% of response time is spent downloading content
    4. 11. “ It all depends on how we look at things, and not how they are in themselves.” - Carl G. Jung
    5. 14. Key factor in performance Fewer HTTP Requests Easy to improve on
    6. 15. Sent with static content Slow upstream speed Big cookies
    7. 16. Cookie Size Response Time (Delta) 0 bytes 78 ms ( 0 ms ) 500 bytes 79 ms ( +1 ms ) 1000 bytes 94 ms ( +16 ms ) 1500 bytes 109 ms ( +31 ms ) 2000 bytes 125 ms ( +47 ms ) 2500 bytes 141 ms ( +63 ms ) 3000 bytes 156 ms ( +78 ms ) Times are for page loads on DSL (~800 kbps).
    8. 17. Eliminate unnecessary cookies Keep sizes low Appropriate domain levels Set Expires date appropriately
    9. 18. Be aware of max connection limits in browsers CNAME to point multiple sub domains to the same IP
    10. 19. One domain = 2 Parallel connections
    11. 20. Two domains = 4 Parallel connections
    12. 21. Too many hostnames can cause complications 2 – 4 sub domains is a good average
    13. 22. Combining 6 scripts into 1 eliminates 5 requests Challenges: <ul><ul><li>develop as separate modules
    14. 23. combinations vs. loading more than needed </li></ul></ul>
    15. 24. JS does not comply with the parallel downloading rule
    16. 25. script defer attribute is not a solution <ul><ul><li>blocks rendering and downloads in FF
    17. 26. slight blocking in IE </li></ul></ul>Solution: move them as low in the page as possible
    18. 27. Crushes the files Strips out all cruft Voodoo magic
    19. 28. JSMin Dojo Shrinksafe Packer YUI Compressor
    20. 29. You can affect users download times
    21. 30. <ul>Gzip can be used on </ul><ul><ul><li>JS
    22. 31. CSS
    23. 32. XML
    24. 33. JSON </li></ul></ul>
    25. 34. <ul>Gzip should not be used on </ul><ul><ul><li>Images
    26. 35. PDFs
    27. 36. Compressed data formats </li></ul></ul>
    28. 37. robots.txt favicon
    29. 38. CSS Sprites favicon
    30. 39. Badly optimized Thumbnails PNG can be compacted 50%, no quality loss OptiPNG
    31. 40. Test on slow connections Slow proxies for developers
    32. 41. Data served through a single domain Smart routing software Data closer to the end user – Less latency
    33. 42. Amazon CloudFront
    34. 43. Appropriate dates Cache far in the future Change file names on releases
    35. 44. Firebug Firecookie Yslow Hammerhead
    36. 45. “ Knowledge rests not upon truth alone, but upon error also.” - Carl G. Jung
    37. 46. Questions? Email: [email_address] Twitter: @h