why performance matters
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Response Time in Man-computer Conversational TransactionsRobert B. Miller, 1968
“…participants had to concentrate up to 50% more when using badly performing websites” Foviance
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Context
flickr.com/photos/75959029@N00/3371615134
Slower web performance has a clear and measureable impact on people at a neurological levelhttp://www.radware.com/mobile-eeg2013/
Q: Given that we now know performance is valued by users of machines, how does it impact the machine owners?
A: We study it!
“The results suggest that slower page speed affects the brand on a more global level”http://www.radware.com/mobile-eeg2013/
$$$
+12% +25% -50%
Shopzilla cut load times by 5 secondshttp://velocityconf.com/velocity2009/public/schedule/detail/7709
Amazon, bing and Google all found that as load time increased, revenue (searches) decreasedhttp://velocityconf.com/velocity2009/public/schedule/detail/8523
+s -%
= £
“85% of mobile users expect sites to load at least as fast or faster than sites on their desktop”Strangeloop Networks
What can we do about these issues?Fix them through better dev practices…
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Sp
ee
d (
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)UK Broadband speeds are improving all the time
Ofcom
But users experiences are getting worse
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Load Time (s)
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But users experiences are getting worse
1 2 3 4 5 6 7 8 9 10 > 100
5
10
15
20
25
30
Load Time (s)
Vis
ito
rs (
%)
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3.11s
1.95s1.63s 1.50s 1.44s 1.41s 1.39s 1.38s 1.37s 1.36s
Bandwidth (Mbps)
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oad T
ime
More bandwidth doesn’t matter (much)Mike Belshe
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Round Trip Time (ms)
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ime (
s)Latency has a huge impact on load times
That’s what we recommend anyway, but what are people doing right now?
.flickr.com/photos/10855397@N02/2461847632
HTTP /2(was SPDY)
Multiplexing 1 connection per host
Header Compression
Browser hints to set priorities
… and secure by default!
Understand TCP Slow Start a little better
If we increase our initial congestion windows we can get more content down in our initial single packet!
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