Internet Backbone Index

Doesnt an IP Switch have lower latency and higher pps?

well, since many of the backbone routers have been able to fill
their pipes for quite a while what difference would the "higher pps" make?
If you are already limited by the wire...

as far as latency goes, a rather slow router has a few hundred micro
seconds processing latency - and a "level 3 switch" might have half
that but even if it had 0 latency (kinda hard to do but for the sake
of argument) you would only save a few hundred microseconds per hop
it would take rather many hops to equal one transit latency on most
networks - and could not be found in the interupt-to-application
latency on the reciveing end.

buffering, which is common between switches & routers, has a far
larger impact.