One… Two… Bye.

Before you’ve had time to finish reading this sentence, almost half of online shoppers will have given up on a retail website that hasn’t loaded. Two seconds is all they’ll wait before 40 percent abandon the site, according to Forrester Research. That’s half the time people were prepared to wait three years ago.

This can especially be an issue for retailers using Flash, Java and other technologies that allow a lot of interaction but may slow sites down.

Site monitoring company Keynote Systems points out the importance of monitoring site performance from the same geographic locations from which the majority of customers arrive at their site, and using the same Web browsers most of them are using.

While larger retailers may want to look into hiring a third party monitoring company, smaller merchants can do at least some of this themselves by taking note of where most of their visitors come from and what software they’re using, and checking out their own sites under those conditions (or asking a friend).