Are Today’s Good Practices... Tomorrow’s Performance Anti-Patterns?

http://www.flickr.com/photos/nzbuu/4093456029

Are Today’s Good Practices…Tomorrow’s Performance Anti-Patterns?

@andydavies#VelocityConf, New York

Saturday, 19 October 13

What if …

http://www.flickr.com/photos/willypayne/3116395089

… dataURIs are an anti-pattern?


The ‘humble’ dataURI

url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABkAAAAZCAMAAADzN3VRAAAAGXRFWHRTb2Z0d2FyZQBBZG9iZSBJbWFnZVJlYWR5ccllPAAAAAZQTFRF/wAAAAAAQaMSAwAAABJJREFUeNpiYBgFo2AwAIAAAwACigABtnCV2AAAAABJRU5ErkJggg==)

=


dataURIs for CSS images

Makes a blocking resource larger by including non-blocking resources

• Browser can’t start rendering page until CSS has downloaded *

• Images don’t block

Do they have the same caching lifetime?

* Some browsers defer download of CSS when media query doesn’t match Saturday, 19 October 13

1. Take 50 icons2. Create 50 stylesheets, each with one more dataURI than

previous3. Create matching HTML file for each stylesheet4. Test them all!


Larger CSS download == longer time to RenderStart

500

625

750

875

1000

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49

Ren

derS

tart

- T

TFB

(m

s)

Number of Sprites


We have our rules…http://www.flickr.com/photos/sowrey/2441134911


and we love recipes…http://www.flickr.com/photos/mrsmagic/2247364228


But, what happens when things change?


Browsers already use the network differently


New network protocols are coming here

http://www.flickr.com/photos/jonlachance/3427660741Saturday, 19 October 13

HTTP 1.1

SPDY

Differences in TCP Connection Use


New Standards - opportunities and challengesSaturday, 19 October 13

How much do we rely on inline JavaScript?

http://www.flickr.com/photos/jfraissi/6352877711Saturday, 19 October 13

74% of visitors support async attribute

<script async src="myscript.js"><script>

http://caniuse.com/script-asyncSaturday, 19 October 13

http://caniuse.com/script-async

http://caniuse.com/script-async

Yet, this is how we typically asynchronously load scripts

<script type="text/javascript"> function() { var js = document.createElement('script'); js.async = true; js.src = 'myscript.js'; var e = document.getElementsByTagName('script')[0]; e.parentNode.insertBefore(js, first); })();</script>


XSSSaturday, 19 October 13

Content-Security-Policy

“Content Security Policy, a mechanism web applications can use to mitigate a broad class of content injection vulnerabilities, such as cross-site scripting (XSS)”

http://www.w3.org/TR/CSP/


Example

Content-Security-Policy: script-src http://www.site.com

Can re-enable inline scripts, but increases XSS risk

Content-Security-Policy script-src 'self'

Only allow scripts to be executed if they come from a designated host, disables inline scripts by default.


What other performance enhancements do we rely on JS for?

Guardian split page into

- Content - Enhancements - Leftovers

Others rely on scroll handlers for lazyload


Tested some scenarios, measured the outcomes

http://www.flickr.com/photos/chandramarsono/4324373384Saturday, 19 October 13

Test Environment

- EC2 - Medium Instance - Dublin

- Apache 2.2- GZIP- Keep-Alive- mod_pagespeed- mod_spdy

- WepPageTest, Dulles / Chrome / Cable


http://www.html5xcss3.com/2012/05/html5-template-interio.html

Off the shelf website templateSaturday, 19 October 13

Minimal Optimisations - HTTP 1.1 vs SPDY

SPDY is faster

(GZIP / Keep-Alive / initcwnd 10)

0s 1s 2s 3s 4s 5s 6s

HTTP

SPDY


Waterfall for HTTP Test


Waterfall for SPDY Test


So which rules are most likely to be at risk?

- Split dominant content domains

- Reduce requests- Merging- Sprites- DataURIs


Sharding CSS background: url() images

Sharded page is much slower

0s 1s 2s 3s 4s 5s 6s 7s 8s

Sharded

Not Sharded


Connection to shard opened later

New TCP connectionopened


New connection shouldn’t have been opened

http://www.stevesouders.com/blog/2013/09/05/domain-sharding-revisited/#comment-60146

“Both chrome and firefox will automatically unshard transparently for you when using spdy and both of the sharded hosts are at the same IP address and covered under one SSL cert (e.g. *.example.com).”

Patrick McManus, Mozilla


Sharding <img src=

Sharded page is marginally faster???

Sharded

Not Sharded

0s 1s 2s 3s 4s 5s 6s 7s 8s


Other tests carried out

- Sharding JS / CSS Horrible

- Merging CSS Slower

- Server Push No noticable difference

- jQuery from Google CDN Suprisingly quick


It’s only going to get more complex

http://www.flickr.com/photos/freshwater2006/693945631

“Situational Performance Optimization, The Next Frontier”

Guy Podjarny


Hmm… How do we move forward?http://www.flickr.com/photos/atoach/6014917153


# Disable concatenation for SPDY/HTTP 2.0 clients

<ModPagespeedIf spdy> ModPagespeedDisableFilters combine_css,combine_javascript</ModPagespeedIf>

# Shard assets for HTTP 1.x clients only

<ModPagespeedIf !spdy> ModPagespeedShardDomain www.site.com s1.site.com,s2.site.com</ModPagespeedIf>

mod_pagespeed & mod_spdy == tools to experiment

High Performance Browser Networking, Ilya GrigorikSaturday, 19 October 13

http://www.flickr.com/photos/simeon_barkas/2557059247

Will complexity lead to the end of hand crafted optimisations?


Start experimenting

http://www.flickr.com/photos/giosp/3933753363Saturday, 19 October 13

Need to improve our toolkit

http://www.flickr.com/photos/alexander/1146677Saturday, 19 October 13

http://www.flickr.com/photos/alexander/1146677

http://www.flickr.com/photos/alexander/1146677

Limits to what protocols or automation can fix

Requests by Domain Bytes by Domain


Thank You!@andydavies

[email protected] http://slideshare.net/andydavies

http://www.flickr.com/photos/nzbuu/4093456029Saturday, 19 October 13

Are Today’s Good Practices... Tomorrow’s Performance Anti-Patterns?

Technology

Transcript of Are Today’s Good Practices... Tomorrow’s Performance Anti-Patterns?