Degraded performance after applying SP4 on SQL 2000

Hi group,

I am seeing degraded performance after applying SP4 on SQL 2000.

My specific queries (they are in stored proc) access linked server.  When
the process is run, I keep seeing blocks on the linked server side among
processes of the same spid spun off from the calling process like this:

A. a process (say spid 58) on initiating server runs, some times shows
blocked by a process (say spid 111) on the linked server, some times not
displaying the block but just continue to run slow;

B. a few processes (spid 111) on the linked server running, often showing
one or two of them blocked by another spid 111.

I have googled and found that there are reports of such slowed down
performance after SP4 application, not necessarily related to the use of
linked server.  There is an explanation by Microsoft why processes could
show being blocked by process of the same spid.  Problem is that it looks
like no solution to the problem and why the switch of locks is so slow.
From what I read other people report, this blocking among processes of the
same spid repeats itself so often that you can easily catch the display of
such blocks in EM.  This is the case by me: when the process is running, I
easily see such blocks with refresh of EM.

My process used to run about 30 sec on SP3a, now it runs some 15 min.  The
only troubleshoot hint I saw sofar is the correct setup of MS DTC, which I
checked on my systems and is set up properly.

Wish to hear from you.

Quentin