The document discusses strategies to enhance page performance in Ruby on Rails applications, including performance tuning workflows, key features in Rails 3 and 3.1, and considerations for mobile and HTML5. It emphasizes the importance of measuring performance, optimizing database queries, and reducing frontend resource loading times. Additionally, it provides various tools and recommendations for effectively improving performance, such as using caching, implementing gzip compression, and minimizing HTTP requests.

1. Faster Page
Performance
John McCaffrey
@J_McCaffrey
http://spkr8.com/t/8314

2. Agenda
• Intro
• Performance 101
• Performance tuning workflow
• Performance features in Rails 3, 3.1
• Considerations for Mobile and HTML 5
• Q&A

3. Intro
• Doing Rails since 2007
• 4th time presenting at WindyCityRails
o 2008: Advanced Firebug and JS unit testing
o 2009: PDF Generation in Rails
o 2010: Rails Performance Tuning
o 2011: Faster Page Performance
• Addicted to Performance Tuning
• railsperformance.blogspot.com
@J_McCaffrey
• Feedback: speakerrate.com railsperformance@gmail.com

4. Intro
• Doing Rails since 2007
• 4th time presenting at WindyCityRails
o 2008: Advanced Firebug and JS unit testing
o 2009: PDF Generation in Rails
o 2010: Rails Performance Tuning
o 2011: Faster Page Performance
• Addicted to Performance Tuning
• railsperformance.blogspot.com
@J_McCaffrey
• Feedback: speakerrate.com railsperformance@gmail.com

5. Intro
• Doing Rails since 2007
• 4th time presenting at WindyCityRails
o 2008: Advanced Firebug and JS unit testing
o 2009: PDF Generation in Rails
o 2010: Rails Performance Tuning
o 2011: Faster Page Performance
• Addicted to Performance Tuning
• railsperformance.blogspot.com
@J_McCaffrey
• Feedback: speakerrate.com railsperformance@gmail.com

6. Intro

7. Intro
• A little about you, and the people around you

8. Intro
• A little about you, and the people around you
• You are all smarter than I am

9. Intro
• A little about you, and the people around you
• You are all smarter than I am
• Try hard to Network today, meet cool people

10. Intro
• A little about you, and the people around you
• You are all smarter than I am
• Try hard to Network today, meet cool people
• Eat lunch with someone new, invite someone
into your ‘crowd’, go to the After Party!!

11. Quick Poll
• Work on a Rails application
• Have been doing Rails for less than 6 months? 1yr? 2yrs? 4yrs?
• Testing Rspec? cucumber? Test::Unit? CI?
• Write Javascript frequently? jQuery? Prototype? js testing?
• Working with Rails 3 or Rails 3.1
• Work on Mobile (native or web)
• Working with HTML 5

12. Quick Poll
• Raise your hand if you Want to learn more
• Stand up if you’d like to meet up with
others and share what you’ve learned

13. Quick Poll
• Raise your hand if you Want to learn more
• Stand up if you’d like to meet up with
others and share what you’ve learned
Don’t knock over your coffee!

14. Help me, Help you!!
• Improving page loading time
• Sql query tuning, indexes or DB tuning
• Rails 3 and 3.1
• HTML 5 and CSS 3
• NoSQL

15. Introduce yourself
(to someone new)
Photo by @monty_ksycki

16. Introduce yourself
(to someone new)
Photo by @monty_ksycki

17. Introduce yourself
(toyou’re from
someone new)
• Name & Where
Photo by @monty_ksycki

18. Introduce yourself
(toyou’re from
someone new)
• Name & Where
• Most important thing you want to
get out of WindyCityRails
Photo by @monty_ksycki

19. Introduce yourself
(toyou’re from
someone new)
• Name & Where
• Most important thing you want to
get out of WindyCityRails
• Only 2mins for this!!!!
Photo by @monty_ksycki

20. Agenda
• Intro
•
•
Performance 101
Performance tuning workflow
• Performance features in Rails 3, 3.1
• Considerations for Mobile and HTML 5

21. Performance Matters
www.strangeloopnetworks.com/web‐performance‐op4miza4on‐hub

22. Perf. statistics
www.strangeloopnetworks.com/web‐performance‐op4miza4on‐hub

23. Perf. statistics
www.strangeloopnetworks.com/web‐performance‐op4miza4on‐hub

24. Increased revenue 12%

25. http://blog.kissmetrics.com/loading-time/

27. So where do we start?

28. Drop some knowledge
"Premature optimization
is the root of all evil"
-Donald Knuth

29. Is it premature?

30. Is it premature?
Effort vs Value
• Gzip
• Adding database indexes
• Optimizing images
• Try nginx (or trinidad)

31. Measuring != Premature
‘Good Enough’ metrics
• Avg response time
• Server Load
• Memory footprint
• Slow queries
• Load capacity

32. Perf Tuning Pledge

33. Perf Tuning Pledge
• “I will MEASURE before and after”

34. Perf Tuning Pledge
• “I will MEASURE before and after”
• “I will document and share the findings”

35. Perf Tuning Pledge
• “I will MEASURE before and after”
• “I will document and share the findings”
• “WE will decide to monitor it, fix it, or just
forget it”

36. Agenda
• Intro
• Performance 101
• Performance tuning workflow
• Performance features in Rails 3, 3.1
• Considerations for Mobile and HTML 5

37. Perf tuning workflow
• Page load
• Application tuning
• DB performance
• Javascript
• Architecture*

38. Improving page load

39. Improving page load
Yslow (Firefox and Chrome)
http://developer.yahoo.com/yslow/
Page speed (Firefox and Chrome)
http://code.google.com/speed
Dynatrace (IE and Firefox)
http://ajax.dynatrace.com
Webpagetest.org (IE, Chrome, Firefox)

40. Improving page load
Yslow (Firefox and Chrome)
http://developer.yahoo.com/yslow/
Page speed (Firefox and Chrome)
http://code.google.com/speed
Dynatrace (IE and Firefox)
http://ajax.dynatrace.com
Webpagetest.org (IE, Chrome, Firefox)

41. Improving page load
Yslow (Firefox and Chrome)
http://developer.yahoo.com/yslow/
Page speed (Firefox and Chrome)
http://code.google.com/speed
Dynatrace (IE and Firefox)
http://ajax.dynatrace.com
Webpagetest.org (IE, Chrome, Firefox)

42. Improving page load
Yslow (Firefox and Chrome)
http://developer.yahoo.com/yslow/
Page speed (Firefox and Chrome)
http://code.google.com/speed
Dynatrace (IE and Firefox)
http://ajax.dynatrace.com
Webpagetest.org (IE, Chrome, Firefox)

43. Improving page load
Yslow (Firefox and Chrome)
http://developer.yahoo.com/yslow/
Page speed (Firefox and Chrome)
http://code.google.com/speed
Dynatrace (IE and Firefox)
http://ajax.dynatrace.com
Webpagetest.org (IE, Chrome, Firefox)

44. Improving page load
Yslow (Firefox and Chrome)
http://developer.yahoo.com/yslow/
Page speed (Firefox and Chrome)
http://code.google.com/speed
Dynatrace (IE and Firefox)
http://ajax.dynatrace.com
Webpagetest.org (IE, Chrome, Firefox)
80-85% of the time is spent on the front-end

45. Page load rules
1. Minimize HTTP Requests
2. Use a Content Delivery Network
3. Add an Expires or a Cache-Control Header
4. Gzip Components
5. Put StyleSheets at the Top
6. Put Scripts at the Bottom
7. Avoid CSS Expressions
Steve Souders 8. Make JavaScript and CSS External
9. Reduce DNS Lookups
10. Minify JavaScript and CSS
11. Avoid Redirects
12. Remove Duplicate Scripts
13. Configure ETags
14. Make AJAX Cacheable
15. Use GET for AJAX Requests
16. Reduce the Number of DOM Elements
17. No 404s
18. Reduce Cookie Size

46. Waterfall 101

47. • Typically 80% of the browsers ‘effort’ is spent
loading all the other stuff after the initial html

48. Waterfall 101

49. Waterfall 101

50. Waterfall 101

51. Waterfall 101

52. Waterfall 101
Javascript execution is blocking the next download

53. Waterfall 101

54. Waterfall 101
Css shouldn’t block,
what’s going on here?

55. Waterfall 101
<head>
<title>base page</title>
<link type="text/css" rel="stylesheet" href="http://tools.w3clubs.com/1.expires.css">
<!--[if IE 6 ]>
<linktype="text/css" rel="stylesheet"href="http://tools.w3clubs.com/2.expires.css">
<![endif]-->
</head>
www.phpied.com/conditional-comments-block-downloads

56. Waterfall 101
<!--[if IE]><![endif]-->
<head>
<html lang="en">
<title>base page</title>
<head> type="text/css" rel="stylesheet" href="http://tools.w3clubs.com/1.expires.css">
<link
<!--[if IE 6 page</title>
<title>base ]>
<link type="text/css" rel="stylesheet"href="http://tools.w3clubs.com/2.expires.css">
<linktype="text/css" rel="stylesheet" href="http://tools.w3clubs.com/1.expires.css">
<![endif]--> ]>
<!--[if IE 6
<linktype="text/css" rel="stylesheet"href="http://tools.w3clubs.com/2.expires.css">
</head>
<![endif]-->
</head>
www.phpied.com/conditional-comments-block-downloads

57. Save your Waterfall!
HTTP Archive format
(HAR)

58. Save your Waterfall!
HTTP Archive format
(HAR)
• Export options www.softwareishard.com/blog/har-adopters
• Firebug
• IE9
• Chrome
• Webpagetest.org
• Har viewer www.softwareishard.com/har/viewer
• Compare multiple files

59. Save your Waterfall!
HTTP Archive format
(HAR)
• Export options www.softwareishard.com/blog/har-adopters
• Firebug
• IE9
• Chrome
• Webpagetest.org
• Har viewer www.softwareishard.com/har/viewer
• Compare multiple files
Did I mention that its important to measure?

60. Solutions
• Gzip
• Combine and minify js and css
• Load css first, js at the bottom
• Optimize images and use css sprites
• Use a cdn for static assets
• Defer javascript loading

61. Deferred loading of
javascript

62. Deferred loading of
javascript
• Load only the minimum necessary javascript first
• Load the rest of the javascript asynchronously
• Pre-load and pre-cache javascript and images for
the next pages

63. Deferred loading of
javascript
• Load only the minimum necessary javascript first
• Load the rest of the javascript asynchronously
• Pre-load and pre-cache javascript and images for
the next pages
bit.ly/non-blocking-js
www.stevesouders.com/blog/2009/04/27/loading-scripts-without-blocking

64. Leverage
✓ Those changes improve the
performance across multiple
requests
✓ Well tested, well understood
✓ Continues to be useful as new
features are added, won’t get
in your way

65. Leverage
✓ Those changes improve the
performance across multiple
requests
✓ Well tested, well understood
✓ Continues to be useful as new
features are added, won’t get
in your way

66. Perf tuning workflow
• Page load
• Application tuning
• DB performance
• Javascript

67. Backend performance

68. Backend performance
2 seconds?
What’s taking so long?

69. Tools
• Request log analyzer
• Splunk
• New Relic
• Rack::Bug
• Built in Benchmark and profiling tools

70. What I’m looking for

71. What I’m looking for
• What is the average response time
• What is the slowest request
• What request makes up the majority of the
work the server is doing
• Are there good candidates for caching?

72. Common culprits
• Not leveraging the database
• Too much memory
• Too many queries
• Generally slow code
• Loading more fields than needed

73. N +1
clients = Client.limit(10)
clients.each do |client|
puts client.address.postcode
end

74. N +1
1 query to clients = Client.limit(10)
load the clients clients.each do |client|
puts client.address.postcode
end

75. N +1
1 query to clients = Client.limit(10)
load the clients clients.each do |client|
puts client.address.postcode
end
1 query for each address (x10)

76. N +1
1 query to clients = Client.limit(10)
load the clients clients.each do |client|
puts client.address.postcode
end
1 query for each address (x10)
clients = Client.includes(:address).limit(10)
clients.each do |client|
puts client.address.postcode
end

77. N +1
1 query to clients = Client.limit(10)
load the clients clients.each do |client|
puts client.address.postcode
end
1 query to 1 query for each address (x10)
load the clients
clients = Client.includes(:address).limit(10)
clients.each do |client|
puts client.address.postcode
end

78. N +1
1 query to clients = Client.limit(10)
load the clients clients.each do |client|
puts client.address.postcode
end
1 query to 1 query for each address (x10)
load the clients
clients = Client.includes(:address).limit(10)
clients.each do |client|
puts client.address.postcode
end
1 query to get all 10 Addresses!

79. Libraries

80. Libraries
• Document why you have it
• Remove unused, reduce dependencies
• Pick between duplicate tools
• Try to stay current
• Rvm, bundler and git branches for testing
• “Is it safe to upgrade that library” - find the
right balance of tests to answer this

81. Perf tuning workflow
• Page load
• Application tuning
• DB performance
• Javascript

82. DB Tuning
• Slow Queries
• Not enough server resources
• Not balanced for Read/Write usage

83. Tools
• Rails log
• Slow query log
• launchpad.net/percona-toolkit
• Explain
• Server profiling (CPU, IO, Mem, etc)

84. Explain
Aggregate (cost=154115.13..154115.14 rows=1 width=4) (actual time=4760.885..4760.886 rows=1 loops=1)
->Nested Loop Left Join (cost=0.00..154115.11 rows=9 width=4) (actual time=3262.981..4760.794 rows=2)
Join Filter:(parts.id = lines_bills.part_id)
->Nested Loop Left Join (cost=0.00..154100.44 rows=9 width=8) (actual time=3262.954..4760.608 rows=2)
->Nested Loop (cost=0.00..153983.24 rows=8 width=4) (actual time=3262.940..4760.574 rows=2 loops=1)
->Seq Scan on bills (cost=0.00..153822.17 rows=11 width=4) (actual time=3262.813..4760.361 rows=2)
Filter:(((bill_type)::text = 'Personal'::text) AND (upper((ssn)::text) ~~ '%333901151%'::text))
->Index Scan using lines_idx1 on lines (cost=0.00..14.63 rows=1 width=4) (actual time=0.093..0.094)
Index Cond: (lines.bill_id = bills.id)
Filter:((NOT lines.archived) AND ((lines.status)::text <> 'created'::text))
->Index Scan using lines_idx1 on lines lines_bills (cost=0.00..14.62 rows=2 width=8)
Index Cond:(lines_bills.bill_id = bills.id)
->Seq Scan on parts (cost=0.00..1.28 rows=28 width=4) (actual time=0.010..0.045 rows=30 loops=2)
Total runtime: 4761.401 ms

85. Explain
Aggregate (cost=154115.13..154115.14 rows=1 width=4) (actual time=4760.885..4760.886 rows=1 loops=1)
->Nested Loop Left Join (cost=0.00..154115.11 rows=9 width=4) (actual time=3262.981..4760.794 rows=2)
Join Filter:(parts.id = lines_bills.part_id)
->Nested Loop Left Join (cost=0.00..154100.44 rows=9 width=8) (actual time=3262.954..4760.608 rows=2)
->Nested Loop (cost=0.00..153983.24 rows=8 width=4) (actual time=3262.940..4760.574 rows=2 loops=1)
->Seq Scan on bills (cost=0.00..153822.17 rows=11 width=4) (actual time=3262.813..4760.361 rows=2)
Filter:(((bill_type)::text = 'Personal'::text) AND (upper((ssn)::text) ~~ '%333901151%'::text))
->Index Scan using lines_idx1 on lines (cost=0.00..14.63 rows=1 width=4) (actual time=0.093..0.094)
Index Cond: (lines.bill_id = bills.id)
Filter:((NOT lines.archived) AND ((lines.status)::text <> 'created'::text))
->Index Scan using lines_idx1 on lines lines_bills (cost=0.00..14.62 rows=2 width=8)
Index Cond:(lines_bills.bill_id = bills.id)
->Seq Scan on parts (cost=0.00..1.28 rows=28 width=4) (actual time=0.010..0.045 rows=30 loops=2)
Total runtime: 4761.401 ms
changed (upper(ssn) LIKE E'%123456789%')
to (ssn LIKE E'123456789%') Total runtime: 7.579ms

86. Explain
Aggregate (cost=154115.13..154115.14 rows=1 width=4) (actual time=4760.885..4760.886 rows=1 loops=1)
->Nested Loop Left Join (cost=0.00..154115.11 rows=9 width=4) (actual time=3262.981..4760.794 rows=2)
Join Filter:(parts.id = lines_bills.part_id)
->Nested Loop Left Join (cost=0.00..154100.44 rows=9 width=8) (actual time=3262.954..4760.608 rows=2)
->Nested Loop (cost=0.00..153983.24 rows=8 width=4) (actual time=3262.940..4760.574 rows=2 loops=1)
->Seq Scan on bills (cost=0.00..153822.17 rows=11 width=4) (actual time=3262.813..4760.361 rows=2)
Filter:(((bill_type)::text = 'Personal'::text) AND (upper((ssn)::text) ~~ '%333901151%'::text))
->Index Scan using lines_idx1 on lines (cost=0.00..14.63 rows=1 width=4) (actual time=0.093..0.094)
Index Cond: (lines.bill_id = bills.id)
Filter:((NOT lines.archived) AND ((lines.status)::text <> 'created'::text))
->Index Scan using lines_idx1 on lines lines_bills (cost=0.00..14.62 rows=2 width=8)
Index Cond:(lines_bills.bill_id = bills.id)
->Seq Scan on parts (cost=0.00..1.28 rows=28 width=4) (actual time=0.010..0.045 rows=30 loops=2)
Total runtime: 4761.401 ms
changed (upper(ssn) LIKE E'%123456789%')
to (ssn LIKE E'123456789%') Total runtime: 7.579ms
then to (ssn = E'123456789') Total runtime: 1.696ms

87. Culprits

88. Culprits
• Too many queries
• No indexes on the key data
• Not optimized for how the db ‘thinks’
• Not enough server memory for sorting
• Trying to do too much in one query

89. Testing

90. Testing
• Measure first!
• Make performance tuning changes in the
most tested parts of the app
• Have the most important parts of your app
well-tested, so tuning will be easier
• Well-tested code tends to be well factored

91. Perf tuning workflow
• Page load
• Application tuning
• DB performance
• Javascript

92. Javascript is powerful

93. Javascript is powerful
• Most hate for javascript is really a hatred of
the browser and DOM interaction

94. Javascript is powerful
• Most hate for javascript is really a hatred of
the browser and DOM interaction
• Javascript is driving a lot of very cool things

95. Javascript is powerful
• Most hate for javascript is really a hatred of
the browser and DOM interaction
• Javascript is driving a lot of very cool things
• Node.js

96. Javascript is powerful
• Most hate for javascript is really a hatred of
the browser and DOM interaction
• Javascript is driving a lot of very cool things
• Node.js
• Backbone

97. Javascript is powerful
• Most hate for javascript is really a hatred of
the browser and DOM interaction
• Javascript is driving a lot of very cool things
• Node.js
• Backbone
• sproutCore

98. High performance js
• UI thread is responsible for js
and UI updates
• Understand Repaint and Reflow
triggers
• Benchmarks for browser
performance
• Dom Scripting
• Memory and cpu usage

99. Javascript profiling
• Dynatrace
• Google Speed tracer
• Firebug profiler

100. Dynatrace Ajax (IE and Firefox)
http://blog.dynatrace.com/2010/07/22/ie-compatibility-view-how-to-identify-performance-
problems-between-ie-versions/

101. Dynatrace Ajax (IE and Firefox)
http://blog.dynatrace.com/2010/07/22/ie-compatibility-view-how-to-identify-performance-
problems-between-ie-versions/

103. jQuery Top Issues

104. jQuery Top Issues
• Poor selector usage
• $(‘#Id, form, input’) Id and element are fast
• $(‘.classname’) causes full scan in IE5-8

105. jQuery Top Issues
• Poor selector usage
• $(‘#Id, form, input’) Id and element are fast
• $(‘.classname’) causes full scan in IE5-8
• show() and hide() often slower
than .addClass(“show”) or .addClass(“hide”)

106. jQuery Top Issues
• Poor selector usage
• $(‘#Id, form, input’) Id and element are fast
• $(‘.classname’) causes full scan in IE5-8
• show() and hide() often slower
than .addClass(“show”) or .addClass(“hide”)
• .each() often slower than regular ‘for’ loop

107. jQuery Top Issues
• Poor selector usage
• $(‘#Id, form, input’) Id and element are fast
• $(‘.classname’) causes full scan in IE5-8
• show() and hide() often slower
than .addClass(“show”) or .addClass(“hide”)
• .each() often slower than regular ‘for’ loop
• Avoid extra queries by caching selector

108. jQuery Top Issues
• Poor selector usage
• $(‘#Id, form, input’) Id and element are fast
• $(‘.classname’) causes full scan in IE5-8
• show() and hide() often slower
than .addClass(“show”) or .addClass(“hide”)
• .each() often slower than regular ‘for’ loop
• Avoid extra queries by caching selector
• Avoid manipulating the Dom in a loop, try to
append all at once (with a wrapping element)

109. Browser Comparison

110. Browser Comparison
• jsperf.com
• Compare js performance across browsers
• http://jsperf.com/queryselectorall-vs-
getelementsbytagname

111. Browser Comparison
• jsperf.com
• Compare js performance across browsers
• http://jsperf.com/queryselectorall-vs-
getelementsbytagname
• jsfiddle.net (full page structure)
• http://jsfiddle.net/addyosmani/BFeMN/

112. Browser Comparison
• jsperf.com
• Compare js performance across browsers
• http://jsperf.com/queryselectorall-vs-
getelementsbytagname
• jsfiddle.net (full page structure)
• http://jsfiddle.net/addyosmani/BFeMN/
These tools make benchmarks easier and repeatable

113. Agenda
• Intro
• Performance 101
• Performance tuning workflow
• Performance features in Rails 3, 3.1
• Considerations for Mobile and HTML 5

114. Performance features in Rails 3
• Separation of framework, only load what you need
• New Active Record Arel query structure
• http://www.slideshare.net/tenderlove/zomg-why-
is-this-code-so-slow
• Bundler
• Ruby 1.9.2 (with patch for faster Rails 3 load)

115. Performance features in Rails 3.1

116. Performance features in Rails 3.1
• JQuery by default

117. Performance features in Rails 3.1
• JQuery by default
• Prepared statement caching

118. Performance features in Rails 3.1
• JQuery by default
• Prepared statement caching
• New Asset Pipeline

119. Performance features in Rails 3.1
• JQuery by default
• Prepared statement caching
• New Asset Pipeline
• railscasts.com/episodes/279-understanding-the-asset-pipeline

120. Performance features in Rails 3.1
• JQuery by default
• Prepared statement caching
• New Asset Pipeline
• railscasts.com/episodes/279-understanding-the-asset-pipeline
• Http Streaming

121. Performance features in Rails 3.1
• JQuery by default
• Prepared statement caching
• New Asset Pipeline
• railscasts.com/episodes/279-understanding-the-asset-pipeline
• Http Streaming
• railscasts.com/episodes/266-http-streaming

123. Html 5 is a big deal!
• More tags and native behavior
• Native form elements
• Client side Validation
• http://slides.html5rocks.com
• http://mrdoob.com/91/Ball_Pool
• http://bodybrowser.googlelabs.com
• http://www.chromeexperiments.com/

124. Mobile

125. Mobile
• Good for ‘desktop’ and mobile

126. Mobile
• Good for ‘desktop’ and mobile
• Reduce network calls

127. Mobile
• Good for ‘desktop’ and mobile
• Reduce network calls
• Only load what you need

128. Mobile
• Good for ‘desktop’ and mobile
• Reduce network calls
• Only load what you need
• Cache as much as you can (HTML5 AppCache)

129. Mobile
• Good for ‘desktop’ and mobile
• Reduce network calls
• Only load what you need
• Cache as much as you can (HTML5 AppCache)
• Specific to mobile

130. Mobile
• Good for ‘desktop’ and mobile
• Reduce network calls
• Only load what you need
• Cache as much as you can (HTML5 AppCache)
• Specific to mobile
• Javascript is roughly 10X slower on mobile

131. Mobile
• Good for ‘desktop’ and mobile
• Reduce network calls
• Only load what you need
• Cache as much as you can (HTML5 AppCache)
• Specific to mobile
• Javascript is roughly 10X slower on mobile
• Click events delay for 300-500ms, use touch instead

132. Mobile
• Good for ‘desktop’ and mobile
• Reduce network calls
• Only load what you need
• Cache as much as you can (HTML5 AppCache)
• Specific to mobile
• Javascript is roughly 10X slower on mobile
• Click events delay for 300-500ms, use touch instead
• Smaller Cache (IOS only caches pages under 25kb
unzipped)

133. Browser references
http://developer.yahoo.com/yslow/
http://code.google.com/speed
http://ajax.dynatrace.com
Webpagetest.org
http://ajaxian.com/archives/when-does-javascript-trigger-
reflows-and-rendering

134. jQuery
• http://addyosmani.com/jqprovenperformance
• http://www.learningjquery.com/2010/05/now-
you-see-me-showhide-performance
• http://www.learningjquery.com/2009/03/43439-
reasons-to-use-append-correctly

135. javascript
• Find a mentor: http://jsmentors.com
• play around: http://jsfiddle.net/addyosmani/BFeMN
• run tests and share them: jsperf.com
• speed of different tools: dante.dojotoolkit.org/taskspeed

136. Thank You!
Any Questions?
railsperformance.blogspot.com
railsperformance@gmail.com
@J_McCaffrey