This document provides guidelines and techniques for profiling and optimizing performance. It recommends measuring performance metrics, prioritizing front-end optimizations like reducing file sizes and HTTP requests before backend optimizations, and optimizing code last after other techniques. Specific techniques discussed include minifying assets, compressing images, adding caching, using developer tools to identify issues, and PHP profiling tools like XHProf and XDebug.

1. PROFILING & OPTIMIZATION
Tools, guidelines, and techniques

2. PERFORMANCE

3. WHY BOTHER?

4. HIGHER CONVERSION RATES

5. SLOW MOBILE
CONNECTIONS

6. CONSERVE CAPACITY

7. RULES; MORE LIKE
GUIDELINES

8. Guideline
MEASURE EVERYTHING

9. Guideline
HUNT THE BIG FISH

10. Guideline
START CHEAP & ITERATE

11. Cost Order
Minify assets
Compress images
Reduce the number of HTTP requests
Optimize database queries
Add caching
Code optimization

12. JUNK UP FRONT

13. Junk Up Front

14. Measuring
Chrome developer tools

15. Junk up front
Number of requests
Number of hosts
Image count & image size
Script count & script size

16. Fixing
Smushit (pngcrush, jpegtran, imagemagick)
Uglify.js, CSSMin
Make, phing, rake, grunt, shell scripts
Image sprites

17. Guideline
AVOID WORK TO GO FASTER

18. WEBSERVER TRICKS

19. Measuring
Chrome developer tools

20. Webserver tricks
GZIP all the things.
Far Future cache headers.
Consider a CDN.

21. SQL MOLASSES

22. Database slowness
Many backend performance issues are caused by too many, or
slow queries.
Mysql has a pretty terrible query planner.
Sub-queries and derived table joins will eventually catch fire.
Slow query logs, mtop, or monitoring like new relic are your best
friend.

23. Database slowness
Slow query logs - Percona makes great tools for MySQL.
Disable query caching.
Run EXPLAIN on slow queries.
Add indexes/tweak queries, and repeat.

24. Explain Queries
Visual explain makes it easier.

25. Indexes
Index commonly used columns.
Column order in matters in indexes.

26. CACHING

27. Caching
Can be expensive to rollout, if you need new infrastructure
Cache expiration is really really hard.

28. What to Cache
Results that don’t change often
Use monitoring/analytics to find the busiest pages.
Start using caching there.
Expand once you’ve learned more.

29. Where to cache
Hopefully in Memcache/Redis
Failing that in Apc/Wincache
Files - Sometimes not faster.

30. Optimize cache use
Watch cache miss rate.
Tune cache expiration so you miss less often.

31. Guideline
OPTIMIZE CODE LAST,
MOST OF THE TIME

32. JAVASCRIPT

33. PHP

34. Javascript tools
Chrome dev tools are the gold standard.
CPU profiles are invaluable.
Heap comparisons can be used to find memory leaks.

35. Cpu Profiler
Chrome dev tools

36. Cpu Profiler
Chrome dev tools

37. Cpu Profiler
Chrome dev tools

38. Cpu Profiler
Chrome dev tools

39. PHP TOOLS

40. Debug Kit
Deeper insights into CakePHP

41. XHProf
PECL extension produced by Facebook.
Captures runtime metrics at a function level.
Possible to use in a sub-sample of production unlike xdebug.

42. Xhgui
Nicer UI to XHProf data

43. Xhgui
Nicer UI to XHProf data

44. XDebug
Not suitable for servers with traffic,
Very detailed results.

45. Webgrind
XDebug UI

46. Other PHP tweaks
Opcode caching is a must.
Don’t use file based sessions.

47. RECAP

48. MEASURE EVERYTHING

49. BE THRIFTY

50. START IN THE FRONT

51. AVOID WORK

52. OPTIMIZE CODE

53. THANKS