tried to do too much
Instead of blockquoting the entire Ars Technica piece on Wil Shipley's Delicious Library 2, I'll just grab this bit.
For instance, a memory leak in the display of PNG graphics led to major performance hits and eventual crashes for users with thousands of items. Unfortunately, no one expected users with these huge libraries to attempt to publish their collections to the web. "Who has that kind of time? Well, it turns out, die-hard collectors do," Shipley said.