Generally speaking even now you can't do route lookups fast enough to handle provider traffic volume with current general-purpose CPUs (although it seems to be on the edge of possible). Instead routes are loaded into special ASICs (TCAM: http://en.wikipedia.org/wiki/Content-addressable_memory) that seem to not follow Moore's Law, be it due to low volume or other limitations (perhaps not technical).

Routers using TCAM seem to max out between 1-2M routes (divided across v4, v6, MPLS, etc). More recent routers are using slightly more flexible processors so there's some hope but the router product cycle is fairly lethargic.