Hacking to be Performant?Talk: Performance Engineering

Speaker: Apoorv Saxena

Time to run a poll

How many you consider#perfmatters?

What performance monitoring tools are you

using?(To evaluate your Front End’s Performance)

How many of you have it as part of your

“Continuous Deployment”?

Enough, let’s start Hacking

What do you mean by “Hacking”?

What do you mean by “Performant”?

Evolution of the Web: Browser & Technologies

EvolutionIs necessary, though it proceeds gradually and takes some time, it accounts for everyone to be on the same page.

Though, not everyone can afford to walk at the same speed, they must run, jump obstacles, cut corners and give their best shot.

Loading Webpages under 1 second

First pixel render time less than 500ms

Running Applications at 60fps

Delivering a Jank Free Experience

#perfmatters

What are we Trying to fit?● HTML5 Games● Single Page Applications● Animations● Editors, Document Collaboration Tools● WebRTC (Video, Audio)and many more.

That’s it?

Not at all.

Everything available on Mobile must be available via APIs on Web.

Let me tell you a story

From JS to Screen:

Style/Layout PaintingJS Compositing

keep < 16ms!

1. Add CSS rules in style via JS.2. Recalculate style, maybe relayout.3. Paint the browser’s mental model to a layer4. Composite all layers into a final image

What causes Jank?

Style/Layout PaintingJS

16ms!

Draw Commands CPU GPU

SCREEN

Extensive Upload

Rasterization in Action

Performance Hacks:

Creating a separate layer for elements requesting

frequent updates

Hardware Accelerationrules me

What about using Canvas instead of DOM?

You must consider:

● Accessibility, Flipboard injects mirror of the content into an invisible dom so it’s still in synch for VoiceOver.

● Canvas is not hardware accelerated on every browser (accompanies device constraints).

DOM Rendering might become amazingly fast soon.

(Hint: remember project Ganesh).

Considered using DOMSprites?

SCREEN

Project Ganesh:

Draw Commands GPU

60fps is not required at every instance

Note: Our eyes are much more attuned to variance than framerate.

A steady 30Hz looks better than 60Hz that misses a few frames a second.

Thank You!

See jankfree.org, html5rocks.com for lots of info