Strong opinions, weakly held

Usability and performance, part 1

I’ve started collecting screen shots that illustrate the problem of performance issues affecting the usability of Web sites. I saw this one in a shopping cart from an online store (I don’t remember which one, and they probably wouldn’t want to be identified anyway).

As you can see, this text was added to the Web page because the “add to cart” request takes a long time to process. To prevent users from adding duplicate items to their cart, the Web site warns the user to keep waiting rather than pressing the button again.

The proper approach would be to improve the shopping cart so that adding items doesn’t take so long, or to find a more robust hosting provider, but those alternatives are more work and more expensive. I’d be willing to bet that the people running the site are using third party software that they can’t fix even if they want to.


  1. …Or how about making the software smarter by teaching it to recognize multiple orders for the same object from the same button? Ask the client to confirm.

    Contraries: Making the software fast enough that clients don’t get impatient is probably a bigger win. And as you say if the seller doesn’t have the ability to fix the shopping cart software advice like this is useless.

  2. Another solution is to use Javascript to change the state of the submit button to “disabled” upon the first click. It’s not as good a solution as fixing the offending slowness/problem with the software but it does solve the problem of the user clicking a button more than once.

  3. Of course you should fix the response speed, but since you probably can’t guarantee the response speed, why not add a hidden field/parameter holding the old-qty so that you can distinguish a duplicate request from an intentional addition?

  4. Hmm, reminds me of all the old MT installations that used to prominently display notices imploring commenters not to press Post more than once.

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