System Response Time and Feedback Guidelines

 

There is no industry standard for application response time1. How long someone is willing to wait is only relevant in the context of how important the task is to them. For example, how long someone is willing to wait to view their family’s online photo album versus how long they are willing to wait for their tax software to confirm that their return has been submitted successfully is much different. And an acceptable response time will vary when someone is at home or are at work or a wireless connection in an airport, etc. There are too many factors to determine a “standard” response time for applications.

Industry Guidelines for Response Feedback

It is not actual response time that people are concerned with but perceived response time. A user-friendly experience provides some indication to the user that the task is occurring, how long the task might take, and how much work has already been done. For this we have industry guidelines to follow2:

Time Feedback
On mouse-over or click Highlight or otherwise give feedback that the item or items have been selected
For delays of more than 1 second Indicate to the user that the system is working on the problem, for example by changing the shape of the cursor
For operations taking between 2 and 10 seconds Provide feedback such as a combination of a “busy” cursor with a rapidly changing number in small field in the bottom of the screen to indicate how much has been done
Anything slower than 10 seconds Provide a percent-done indicator as well as a clearly signposted way for the user to interrupt the operation or continue with other tasks while the operation completes in the background
For operations where it is unknown in advance how much work has to be done Provide running progress feedback of the amount of work done. For example, a system searching an unknown number of remote databases could print the name of each database as it is processed
If it is not possible to provide feedback on work done Provide a less specific progress indicator such as a pinwheel or dots printed on a status line

Fig I: Response Time Guidelines

Notes:

  1. Acceptable application response times vs. industry standard, Scott Barber, March 13, 2007, http://searchsoftwarequality.techtarget.com/tip/0,289483,sid92_gci1243574,00.html
  2. Response Times: The Three Important Limits: Excerpt from Chapter 5 in my book Usability Engineering, http://www.useit.com/papers/responsetime.html