From: Peter Booth <pbooth@...>
Date: 2009-08-26T06:18:06+09:00
Subject: Re: Confirm my Performance Test Against Java?

--Apple-Mail-17-197457345
Content-Type: text/plain;
	charset=US-ASCII;
	format=flowed;
	delsp=yes
Content-Transfer-Encoding: 7bit


On Aug 23, 2009, at 6:08 PM, David Masover wrote:

> On Thursday 20 August 2009 10:22:39 am Ben Christensen wrote:
>>
>
>> It provides a better use experience to the user and (according to  
>> Google
>> and Amazon) increases their usage of the system.
>
> I'm curious what the threshold was for this to make a difference.
>
> Certainly, at a certain point, it doesn't. The difference between 16  
> ms and 0.6
> ms would actually be invisible to the human eye. But while 100 ms vs  
> 50 ms may
> make a difference, I'm skeptical. Users are annoyed at having to  
> wait a tenth
> of a second for a response?



I've spent some time trying to understand this. My impressions ..

Human Factors Research says:
A response is perceived as instantaneous if it occurs within 0.1 or  
0.2 sec
A response is perceived as immediate, and won't interrupt  
concentration, if it occurs within about 0.5 to 1.0 sec
If we speed up a website, then a change thats less than  7% to 18%  
wont be discerned by a user.

The State of the art
Google measured that a 400ms slowdown measurably reduced the number of  
searches per user by 0.76%
Shopzilla invested in performance tuning their website and saw revenue  
increases of 7 to 12%
Bing saw measurable changes in user behavior with slowdowns of 200ms  
but not with slowdowsn of 50ms

State of the Art Data Point: A google search for "state of art  
performance testing" from a slow broadband (ADSL 1.5MB/s) IE7 client  
in Dulles VA has an average response time of 861 ms (entire page)

The State of the practice
The web is slow, unnecessarily slow, sometimes painfully slow.
Most website owners (and most developers)
  dont know that their websites are slow,
and they dont know how to fix them

Above Average Data Point: If you search either meetup.com or LinkedIn  
for "performance testing"
from same client as above both have an average response time of 2.0  
sec (entire page).

Sources
Designing and Engineering Time by Steven Seow
papers from Xerox Parc
The O'Reilly Velocity Conference proceedings for 2007 to 2009
My clients
Remote test tools like Keynote, Neustar, Gomez etc
--Apple-Mail-17-197457345--