This document summarizes a presentation about the hidden costs of web components. It discusses using waterfall charts, domain analysis, and referer analysis to identify slow resources. Domain analysis showed the slowest domains were z.cdn.turner.com and i2.cdn.turner.com. Referer analysis revealed the homepage and a component from z.cdn.turner.com were responsible for most requests and load time to that domain. Different analysis techniques help identify different performance issues like slow hosts, third-party providers, and the sources of specific requests.
13. tracking down the source
“...an HTTP header field that identifies the address of the web page that
linked to the resource being requested.”
http://en.wikipedia.org/wiki/HTTP_referer
14. tracking down the source
Referer Request Count Total Load Time (ms)
homepage (www.cnn.com) 177 34,433
z.cdn.turner.com/xslo/cvp/assets/contain
er/2.0.4.0/cvp_main_container...
44 7,214
ads.cnn.com/html.ng/site=cnn&cnn_page
type=main&cnn_position=728x90...
9 2,977
z.cdn.turner.com/cnn/tmpl_asset/static/w
ww_homepage/2970/css/hplib-min.css
22 2,348
ds.serving-sys.com/BurstingRes//Site-
40150/Type-2/ed3d7348-93fb-4938-8d...
2 2,308
17. when to use what
Waterfall Chart Domain Analysis Referer Analysis
Visually represents a single
page load
Useful for:
● Identifying parser /
render-blocking
assets
● Spotting opportunities
for domain sharding
Aggregates resource load
times by domain
Useful for:
● Finding slow hosts
● Monitoring third-party
providers
Aggregates resource load
times by HTTP Referer
Useful for:
● Assigning costs to
resources
● Tracking down the
source for particular
requests
in the beginning there was the waterfall.
helps identify
render blocking stylesheets
parser blocking scripts
opportunities for domain sharding (lots of blocking)
slow individual requests
use the referer to see the source of every request -- who is responsible for loading this resource?
