Just some data points:

Switch timing being somewhat insignificant comapred to the TCP/IP stacks 
at each end.  The following timings for:

100 BaseT  - 14.99 ms
HiPPI      -  5.83 ms

each went through one switch between the same 2 P-II 200's.  Both networks
were otherwise idle.  HiPPi being ~39% the delay as 100BaseT.

Paul