One reason we moved off it was because it was a bandwidth hog! I believe they had two clients to try and help with this, a thin and think client. Even with the thin one, with the CC servers hosted in the states and some developers located in Europe, it would take a half hour for the client to refresh and pull down the latest changes.
Interesting. It was never an issue for us, as we were close to the CC servers. Some folks were not, so they ran their dev/build locally ("network close" to th CC servers) and VNC'd in from their actual location. In that case, only the stuff on the screen had to transit the "far away" network. Although, I think today, network issues would be less of a thing...as I tend to think that networks have scaled faster than code base size. I could be horribly wrong about that though. Any centralized repo is going to have this challenge though. It also depends on if you prefer snapshot or dynamic views. Snapshots were much easier on the network, at the expense of consistency. I also remember the CC team could work magic at optimizing things if you gave them time and a bit of flexibility. Crappy config specs were hard to read, and often slow to work off of. Any config spec that I had to scroll...I knew I was in for a shit week.