Re: [IxDA] What makes an application feel fast?

6 Nov 2010 - 2:34pm
4 years ago
1 reply
1668 reads
Dan Saffer

From Jakob Nielsen, 1993:

"The basic advice regarding response times has been about the same for thirty years [Miller 1968]:

0.1 second is about the limit for having the user feel that the system is reacting instantaneously, meaning that no special feedback is necessary except to display the result.

1.0 second is about the limit for the user's flow of thought to stay uninterrupted, even though the user will notice the delay. Normally, no special feedback is necessary during delays of more than 0.1 but less than 1.0 second, but the user does lose the feeling of operating directly on the data.

10 seconds is about the limit for keeping the user's attention focused on the dialogue. For longer delays, users will want to perform other tasks while waiting for the computer to finish, so they should be given feedback indicating when the computer expects to be done. Feedback during the delay is especially important if the response time is likely to be highly variable, since users will then not know what to expect."

The original article Nielsen cites:

Miller, R. B. (1968). Response time in man-computer conversational transactions. Proc. AFIPS Fall Joint Computer Conference Vol. 33, 267-277.

PDF here:



9 Nov 2010 - 4:57am
Simon Raess

Hey Dan,

Here's an abstract to a study I found after I did some desk research based on your answer. Thought this might be interesting for you, too:

"For years, software engineers have been told that applications must respond to user events within 100 milliseconds to seem instantaneous, yet this assumption has never been systematically tested. In this research, we attempt to establish thresholds of detection for changes in a graphical user interface using adaptive tracking. For keyboard interactions, subjects did not notice delays of approximately 150 milliseconds. In contrast, for mouse interactions, subjects did not notice delays of up to 195 milliseconds. Given these findings, further research is clearly needed to firmly establish lower bounds on application responsiveness so that software and operating system engineers can more precisely tune the interactive real-time responsiveness of their systems."


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