Friendster is an obvious example that comes to mind:
http://www.nytimes.com/2006/10/15/business/yourmoney/15frien...
As Friendster became more popular, its overwhelmed Web site became slower. Things would become so bad that a Friendster Web page took as long as 40 seconds to download. Yet, from where Mr. Lindstrom sat, technical difficulties proved too pedestrian for a board of this pedigree. The performance problems would come up, but the board devoted most of its time to talking about potential competitors and new features, such as the possibility of adding Internet phone services, or so-called voice over Internet protocol, or VoIP, to the site.