Latency matters
Chris Bailey of Adwerx
100ms or less is instantaneous.
100ms of latency costs 1% of sales according to Amazon.
Anatomy of a transaction
Key metrics
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Page load time
47% of people expect a web page to load in 2 seconds or less.
40% will abandon if takes more than 3 seconds to load.
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Start render time
User starts to feel in control when page starts to render.
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Time to first byte
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Page size
Average size of page is 2.2MB, including HTML, stylesheets, images, etc.
Doubled since 2010. Avg. size in 2005 320kB.
Synthetic vs. Real-User Metrics (RUM)
Synthetic can be measured using real browsers in AWS.
RUM can be very skewed based on user connection types.
Tools
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www.webpagetest.org
"Using WebPageTest" book from O'Reilly
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Google analytics
Displays real-user metrics
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New Relic Browser
- Real-user metrics
- Splits time into web app, network, browser
- Can view entire session activity for random users
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Chrome dev tols
window.performance in JS console
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New Relic APM
Monitor performance of web app server
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YSlow
- From Yahoo
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Google PageSpeed Insights
- Similar to YSlow
Pareto principle
80% of effect com from 20% of causes
What worked for Adwerx
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Switch CDN from Amazon CloudFront to Fastly
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Image optimization
- image_optim
- Home page from 3.2MB to 2.6MB
8-9s down to ~6s per load with minimal changes, assistance from Fastly engineer.