I believe the change in performance came during the major MD->MI migration
   which was, IIRC, sometime around 1.2C[?] which was [IIRC] October/November/
   December 199_6_.

[ i've said this a number of times so far, but here it is again ]

as far as i was able to determine, there were two distinct points where
serial performance got worse.  once between oct 3 and oct 19, 1996, when
i started seeing a few more overruns, and then once around dec 31, when
my serial port became unusable at 38400 (IPX).
   
   I'm completely baffled as to why only now we're getting around to
   discussing it when it's been a problem for the last year.

well, *i've* certainly been discussing it for the past year  :-)