I have CamiOptions installed but not CamiBlock (I tried it and it was getting a few too many false-positives... so I uninstalled it). I haven't really noticed Camino slowing down since installing CamiOptions, thought. In fact, I installed it so that I could turn on pipelining and immediate page rendering. If anything, I've noticed a slight speed bump.
That being said, it wouldn't surprise me if CamiBlock was slowing down connection to ad servers (or really just slowing down rendering in general for that matter). I don't know the technicalities behind how it works, but I'd assume it would be comparing server names to the list of blocked servers every time a connection was made - which would slow things down a little.
Side note: MacNN has always been slow to load for me. Maybe it's just my location or something... I don't know.