The killer isnt just routing tables. The killer is lookup time. Cisco stuff
is supposed to flake out at about 40,000 routes from figures people have
quoted. Hence the fact sprint and folks won't route smaller than a /19 and
keep making noises abou going to /17.
I would imagine some other kit can do better some worse, nevertheless trying
to look up destinations from 40,000 choices at 100Mbits/second on 10 network
ports, while recomputing the routing tables is NOT a trivial problem.
Alan