Why performance matters: Measuring your websites performance

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Measuring your websites performance Patrick Hamann Front-end London - April 2013 Why performance matters

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Who am I? • @patrickhamann • Client-side developer • Performance geek

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Who I work for

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What am I going to cover?

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What am I going to cover? • Why performance matters

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What am I going to cover? • Why performance matters • How to measure your websites performance bottlenecks

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What am I going to cover? • Why performance matters • How to measure your websites performance bottlenecks • Myths, tips and best practices

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Ideal load time?

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< 3 secs

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Reality:

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7.25 secs

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Page weight is increasing YoY Source: HTTPArchive

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1.4 Mb

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User load time expectations Source: Web Performance Today

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71% of users want your mobile site to load as fast as the desktop equivalent. Source: Gomez

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"We made the new platform 60% faster and this resulted in a 14% increase in donation conversions." Kyle Rush - Obama Campaign

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Measuring performance Tools

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The critical path Network Parse Paint

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Waterfall analysis

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Size

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Size Latency

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Size Latency Download

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Size Latency Download DOMContentReady

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Size Latency Download DOMContentReady Load

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WebPageTest.org

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WebPageTest.org

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WebPageTest.org

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WebPageTest.org

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WebPageTest.org

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WebPageTest.org

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WebPageTest : Comparison

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WebPageTest : Video

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PROBLEMS

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Common performance bottlenecks • Latency • Payload • Caching • Paint

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Latency • Time to ﬁrst byte (TTFB) • Incurred on every request • Much worse on mobile • CDN’s • The closer to the user, the lower the latency • Edge side compression • HTML ?!

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Reduce payload: 101 • Compression • GZip (mod_deflate mod_pagespeed) • Concatenate CSS/JS • Defer to load event (lazy-load) • Conditional loading • Cache

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Reduce payload: CSS • Only resource that should block the parser! • Load only bare minimum for page chrome • Conditionally load the rest • Browsers download CSS they don't need : e.g. print, tv, device-ratio... • Serve of same host - no DNS lookup • Inline ?*&%!

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WTF!

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Reduce payload: Images • Compression: • Photoshop 60% > ImageOptim 25/70% • Progressive JPEGs • WebP • Base64 icons or icon fonts • Clean SVGs • No images at all?

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Progressive JPEGs Source: Performance calendar

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WebP - Content negotiation WebP lossless images are 26% smaller in size compared to PNGs. WebP lossy images are 25-34% smaller in size compared to JPEG Source: NetDNA blog

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Caching • Far-future cache headers • Invalidation • AppCache is broken :( • Mobile is harder • Smaller shared cache • Stuff critical assets in localStorage

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WTF!

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Render • Don't use setTimeout • Use request animation frame instead. • CSS Animations get over these issues. • Avoid recalculation • Bisecting slow CSS styles & elements

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Render: Timeline Source: Addy Osmani

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Continuous paint mode Source: HTML5 Rocks

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R.U.M

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Navigation timing API Source: W3C

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Navigation timing API Source: W3C

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Google Analytics: Site Speed

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HAR

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Automation: PhantomJS & YSlow Source: Ilya Grigorik

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Automation: HAR Storage Source: https://code.google.com/p/harstorage/

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Automation: CI Integration Build Test Deploy Users Monitor

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Automation: CI Integration Build Test Deploy Users Monitor YSlow

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The Future

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The Future • SPDY/HTTP 2.0

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The Future • SPDY/HTTP 2.0 • Responsive images

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The Future • SPDY/HTTP 2.0 • Responsive images •

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The Future • SPDY/HTTP 2.0 • Responsive images • • Application controller

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The Future • SPDY/HTTP 2.0 • Responsive images • • Application controller • WebP

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The Future • SPDY/HTTP 2.0 • Responsive images • • Application controller • WebP • Client-hints

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The Future • SPDY/HTTP 2.0 • Responsive images • • Application controller • WebP • Client-hints • RESS?

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It sounds easy... • It’s not • Requires a lot of dev time • Maintenance and upkeep • How do you track regression?

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Performance budget • Optimize an existing feature or asset • Remove an existing feature or asset • Don’t add the new feature or asset