what you're doing, but the database system, or whatever the data store is, is often the bottleneck. Or it's the web servers themselves."
Mistake #4: Not having a backup.
Things always go wrong, of course, so smart companies have a backup system in place.
"Make sure you have backup servers, backup locations," Prusak said. "And also do a dry run. Very often companies do have backups, but the people who need to do it … aren't necessarily experienced at it."
Mistake #5: Overlooking the end user experience.
Most performance testing involves hitting the backend systems as hard as you can, noted Prusak, but don't forget to test the user experience with real web browsers while the site is under stress.
The server response time could become unacceptably slow, for instance. "The user experience might degrade from 5 seconds to 20 seconds," and the shopper will head elsewhere before completing the purchase.
Mistake #6: Not factoring in third-party integration.
"We kind of assume that third-party sites or tags are going to work, but you shouldn't make that assumption," said Prusak.
One solution is to use a technology called asynchronous scripting. "It means the webpage isn't waiting for the third-party script to load in order for the page to load," Prusak said.
Failing to factor in third-party glitches can spell Black Friday disaster.
"There was a client who had a third-party chat system, which allows users to chat with somebody at your store," said Prusak. "That's very common. But if there was a problem with the chat system, the whole page wouldn't load correctly."
Prusak's final piece of advice: Make sure any infrastructure improvements are worth the cost.
"If money were no object, every site could handle a limitless number of users," he said. "At the end of the day, you need to do the math and say, 'If it costs me so-and-so much to handle three times as much [traffic] as I anticipate, is it worth it?'"
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