What is considered a fast or slow load w/ respect to a web page

I just built a web page that is employing several different 开发者_开发技巧javascript elements. I am just curious as to what is considered a fast vs. a slow load time. Mine is coming out to be about 490ms w/ four different javascript pieces. Is that good, bad or average? Wondering if I need to optimize my js elements or not.

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There's a paper from 1991 called “The information visualizer, an information workspace”, by Card et all (Xerox Palo Alto Research Center) that says:

• 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.

A detailed overview can be found here.

Bottom line: if we want a fluid user experience, our apps need to operate at 10+ 'fps' :)

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Just run your site through this tool and you'll know (almost) all there is to know about loading times. Or use Google's Speed Tracer if you use Chrome.

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Try to think from the users point of view:

Instead of measuring the response time of xyz XHR request, consider the function the user wants to perform - "post a comment on this website"? Then measure the total time to achieve that goal. If the users work, as a whole, is too much or takes too long then they will go elsewhere.

eg. I can have 10 XHR functions that return in 15ms each it might seem blazing fast. But if the user has to click 10 different places to post a comment, they're going to get sick of my interface pretty quick too. (extreme example)

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This is going to vary from system to system. But if it's taking less than a few seconds to load everything (completely - dom ready), that's pretty good if you ask me. I recall keeping my entire project size down to about 50kb, back before we had all of this fancy ajax :) Cherish your broadbands and asynchronous calls!

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If I remember well a podcast about StackOverflow (I can't find which one it is anymore, on DNR or on Hanselminute), above 1 sec the user starts to have the time to be distracted by something else and loose focus. At 10 seconds, I would probably already have closed your page! of course it depends on what kind of action it is. but if it's a repetitive task, 1 second is the maximum I would say. That's what I aim to in general. It feels instant when you go under that limit.

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The general rule of thumb is that the maximum attention span of a web surfer is 10 seconds*. Anything longer and they'll use another site.

*note: I read that somewhere but can't remember where.