What is considered a good response time for a dynamic, personalized web application?

There's a great deal of research on this. Here's a quick summary.

Response Times: The 3 Important Limits

by Jakob Nielsen on January 1, 1993

Summary: There are 3 main time limits (which are determined by human perceptual abilities) to keep in mind when optimizing web and application performance.

Excerpt from Chapter 5 in my book Usability Engineering, from 1993:

The basic advice regarding response times has been about the same for thirty years [Miller 1968; Card et al. 1991]:

• 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.

It depends on what keeps your users happy. For example, Gmail takes quite a while to open at first, but users wait because it is worth waiting for.

I have been striving for < 3 seconds for my applications, but I'm a bit picky when it comes to performance.

If you ask around, they say that people start to lose interest in the >= 7 second range, by 10-15 seconds you have typically lost them, unless you REALLY have something they want or need.

Of course, it lays in the nature of your question, so answers are highly subjective.

The first response of a website is also only a small part of the time until a page is readable/usable.

I am annoyed by everything larger than 10 sec responses. I think a website should be rendered after 5-7 sec.

Btw: stackoverflow.com has an excellent response time!

Our company has a 5 second response time standard limit, and we aim for 2-3 seconds in general. This accounts for 98% of page loads. A few particular tasks are allowed to go up to 15 seconds, but we then mitigate that time by putting up a page and refreshing every 5 seconds telling the user that we are still trying to process the request. That way the user sees that something is happening and doesn't just leave. Although, considering that I work on a website whose users are forced to use for business reasons, they aren't going to leave, but they are capable of complaining quite loudly.

In general, if the processing is going to take more than 5 seconds, put up a temporary page so that the user doesn't lose interest.

I think you will find that if your web app is performing a complex operation then provided feedback is given to the user, they won't mind (too much).

For example: Loading Google Mail.

Not only does it depend on what keeps your users happy, but how much development time do you have? What kind of resources can you throw at the problem (software, hardware, and people)?

I don't mind a couple-few second delay for hosted applications if they're doing something "complex". If it's really simple, delays bother me.

2 to 3 seconds