Make Browsers CRYHow to make a web app painfully slow

Speaker Name, Title@name name

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About me…

Making slow pages

since the 1990s

Once designed

a page with >9 AJAX requests

that blocked rendering

Have incorrectly

implemented browser caching

Overused Webfonts

Used the blink tag

GOOD NEWSHave done none of these things at New Relic

TL;DR THERE IS NO MAGIC WEB PERF SAUCE.

(but sometimes it's good to know what not to do)

The CLIENT / SERVERmodel

HTTP(S)

The CLIENT / SERVERmodel

HTTP(S)

CACHE

CDN

Pages make requests to an average of

DOMAINS20As of October 2016Source: httparchive.org/trends.php

The average number of requests is now

PER PAGE107As of October 2016Source: httparchive.org/trends.php

Average total transfer size is INCREASING

Source: httparchive.org

1,904.58KB

2,218.65KB

2,540.33KB

Sept 2014

Sept 2015

Sept 2016

requests312

secs render

and it takes

15.4

in the ALEXA TOP 10one site makes…

A MODELFOR FRONTEND DEVS

Infrastructure

My precious code

backend system(s)

"the network"

THE FOCUSFOR FRONTEND DEVS

My precious code

Infrastructure

"the network"

backend system(s)

IGNORE THISAT YOUR OWN PERIL

My precious code

Infrastructure

"the network"

backend system(s)

HOW CAN WE MAKE A PAGE AS SLOW AS POSSIBLE?

1. __________

3. __________

4. __________

2. __________

BROWSER

APP

INFRASTRUCTURE

BROWSER

APP

INFRASTRUCTURE

1. Confuse this

3. Don’t optimize

4. Make bad choices here

2. Ignore this

Introducing:The METER OF BROKEN CUSTOMER EXPERIENCE*

Bad C/X

Good C/X

FROM SCIENCE!

https://www.nngroup.com/articles/powers-of-10-time-scales-in-ux/

I'm going for tacos.

That was fast!

Where should I eat lunch?

10000ms

100ms

1000ms

What technical choices can we make to INCREASE BAD C/X?

Web Performance Lab

What we're testing with.

▪Simple web page: some images, JS, HTML, and CSS

▪Running on AWS EC2 (us-west-2) m2-large instance

▪Powered (and monitored) using Go

1400 ms

LET'S MAKE INFRADECISIONS

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Infrastructure: What's the cheapest?

▪ The cheapest EC2 instance money can buy

– t2.nano

– 512 mb memory

– 1 vCPU

t2.nano

INFRASTRUCTURE

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1445 ms

What a deal!

"The t2.nano offers the full performance of a high frequency Intel CPU core if your workload

utilizes less than 5% of the core on average over 24 hours."

Source: https://aws.amazon.com/blogs/aws/ec2-update-t2-nano-instances-now-available/

INFRASTRUCTURE

I WENT TO LUNCH.

INFRASTRUCTURE

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But came back to this... INFRASTRUCTURE

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Page load time went way, way up INFRASTRUCTURE

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LESSON: T2 INSTANCE CPU PERFORMANCE IS VARIABLE.

INFRASTRUCTURE

LET'S WRITE SOME SLOW GO CODE

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EACH PIXEL IS RANDOMLY GENERATEDimg := image.NewRGBA(image.Rect(0, 0, width, height))

for x := 0; x < width; x++ {for y := 0; y < height; y++ { c := color.RGBA{uint8(rand.Intn(255)), uint8(rand.Intn(255)), uint8(rand.Intn(255)), 255}

img.Set(x, y, c) }}

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Doing this is slow (understandably) APP

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But not slow enough... APP

Go sleep

if os.Getenv("SLOW_IMAGE") != "" {time.Sleep(1000 * time.Millisecond)

}

APP

And Go runtime tweaking...

$ GOGC=10 <app>

APP

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5300ms

And then the browser tears up APP

LET'S UNOPTIMIZE THE NETWORK

Some recent data regarding NETWORK LATENCY

https://aws.amazon.com/blogs/aws/now-open-aws-us-east-ohio-region/

us-west-1

us-west-2

us-east-2

68ms

52ms

A very fast TCP primer

▪Opening a new TCP connection is slow, especially over long distances

▪ Different hosts: different connections

▪ Browsers are good at reusing existing connections

▪ SSL adds additional RTs

Server Browser

roundtrip1

2

3

SYN

SYN/ACK

ACK

Data

NETWORK

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Forcing as many open TCP connections

▪Connection: close HTTP header

▪ For every connection, force the browser to re-establish the connection

▪Host OS also needs to open a new socket. Expect slightly more packets

NETWORK

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Increase the bandwidth!

▪Disable all gzip compression

▪Don't minify

▪Set HTTP headers to prevent any caching at any intermediate CDNs, proxies, or the browser

HTTP(S)

CACHE

NETWORK

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TCP Connection Close: Infrastructure View

The number of received packets suddenly spikes...

NETWORK

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TCP Connection Close: App View

Not much to see here

NETWORK

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% of 0ms connection openings

Connection time measured in Insights from New Relic Synthetics

NETWORK

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Results: Opening all the connections

2040ms

NETWORK

Let's increase network latency the easy way

Make the distance between these really far.

NETWORK

Let's increase network latency the easy way

8,561 miles

San FranciscoAWS in Mumbai

NETWORK

Page load gets (slightly) faster in Japan

ap-south-1

NETWORK

And in Singapore, too NETWORK

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Where the bits come from is really important

2460ms

NETWORK

LET'S CONFUSE THE BROWSER

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Delay getting CSS to the client

▪CSS blocks rendering, delay it for more pain.

▪Put it in the <body>

▪Add @imports for good measure.

▪Make CSS extra-complex, uncachable, and far away from the user.

BROWSER

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Block with JavaScript as much as possible

▪Put a lot of libraries in the <head> tag

▪Make that JavaScript do a lot of unnecessary work

▪Avoid the async script attribute

BROWSER

5DIFFERENT FONTS... FROM CHINA

LETS USE

Why not? BROWSER

Why not?

ALLTHE JAVASCRIPT FRAMEWORKS!

LETS USE

BROWSER

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BROWSER

BROWSER

+3400 ms

+500 ms

+19000 ms

+1000 ms

BROWSER

APP

INFRASTRUCTURE

All these decisions can happen in real life for

good reasons.

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∞ ms 800 ms

AggressivelyUnoptimized

AggressivelyOptimized

Fixing it: solutions

Use a Content Delivery Network

Multiple availability

zones, DNS-based routing

Caching correctly

implemented

JS, HTML, and CSS

optimized for not-blocking

Creating a fast app is more than using ______________.

BROWSER

APP

INFRASTRUCTURE

Creating a fast app is more than using ______________.

BROWSER

APP

INFRASTRUCTURE

fast ec2 hosts

Creating a fast app is more than using ______________.

BROWSER

APP

INFRASTRUCTURE

Go

Creating a fast app is more than using ______________.

BROWSER

APP

INFRASTRUCTURE

HTTP/2

Creating a fast app is more than using ______________.

BROWSER

APP

INFRASTRUCTURE

React

BROWSER

NETWORK

APP

INFRASTRUCTURE

Clay SmithDeveloper Advocate

Thank you.