I did a test recently on the 3, running on a 1GHz eMac with 1GB RAM and a 60GB HD, nothing running in the BG, of course. The first thing to notice is that they actually did update camino with all the new crap in firebird. As far as startup, the new camino runs on par with safari, while firebird has turned into bloatware and slows slow as crap. As far as rendering, from what I could tell, safari and camino were pretty much equal. Safari itself is a good deal smaller than either camino or firebird, which is something to note, and somewhere along the lines, mozilla inc. decided not to optimize for crap for OSX, so firebird is a waste of time. This was probably a big mistake by them because nowadays people look for things like speed, simplicity and usability in browsers, which theirs lack entirely on OSX. When rendering larger sites like blizzard.com, safari typically does it slightly faster than camino. Also, the little top bar with the navicons is smaller in safari than in camino, and much smaller than in firebird. Just to compare CPU usage, it was suggested that I opened top in terminal, and what I found was that Safari uses the least CPU resources most of the time, followed by camino and then firebird, and that when hidden, safari is somehow coded to surrender it's resources and drops to a steady 0.0%, while the other browsers continue to bog down the system.
UserAgent: Mozilla/5.0 (Macintosh; U; PPC Mac OS X; en) AppleWebKit/125.2 (KHTML, like Gecko) Safari/125.8