The Add Reference dialog box has to be one of the most hated things of Visual Studio; certainly, it seems to get more than its fair share of tweets along the lines of "Agghh, hit 'Add Reference' by mistake. I'm off for a coffee"!
The reason for the hatred was that the dialog's default tab was the full list of .Net assemblies available on your machine. That's quite a bunch of metadata for VS to go and read and unfortunately it blocked the UI whilst doing so. What made this doubly frustrating, at least for me, is that I rarely wanted...