DECsystem 5800 with 2 processors slower than with 1?

[Michel Fingerhut]

We noticed a significant slow-down of our 5820 (bi-processor 5800) in
response time after upgrading from Ultrix 3.1 (which supports a single
processor) to Ultrix 4.0 (whose "kernel has been enhanced to support
multiple processors executing kernel code").

The local DEC support's reply to my call was that it was a known
"problem" and their advice was to turn off the  2nd CPU until a fix is
found.

I did this, and lo and behold, "ls" runs so much faster... I wonder if by
turning the remaining CPU off I'll get the computing power DEC claims for
the DS5820.