Facebook scored a 6629 on the WatchMouse Site Performance Index (SPI) --earning it the title of worst-performing social networking site in terms of user perception of speed and availability, MediaPost reports.

The test consists of loading the home page from 25 different test points around the world. They also take points off for broken links and images.

According to WatchMouse, "Facebook had a slow load time and recorded more errors than any of the other monitored sites--a likely side effect of the site's immense popularity. The more users want to visit it, the better the chances are that the traffic onslaught will slow servers to a crawl."

On the plus side, this author just reviewed Facebook for BlackBerry for PC Magazine and found it to be pretty fast.

WatchMouse: Facebook is Worst-Performing Social Networking Site [MediaPost]