I've been running LISTSERV 1.8a (and LMAIL 1.2a) for some time now.
Apparently the biggest performance improvements were in user management
on large lists (we have a few of those).
 
   I did a comparison of one week before and after the change and
was pleased to see about 33% less virtual cpu use and over 25% less
non-spool I/O.  The summary from our VMACCT product is included below.
 
   It appears results vary depending on what sort of things your LISTSERV
does so I'd be curious about other's experiences.  Our list owners seem
to like the new MAILTPL format once they get used to it (but with WELCOME
files we don't really use that as much any more).  I have also used the
new exit for one list (to send out a "survey" to potential members) but
I've heard that might be available more directly in a future MAILTPL.
I've also set up the MSGD interface but I'm not sure how much use it will
get.
 
   Marty
 
 
Resource Usage Comparison of LISTSERV 1.7f with 1.8a:
 
  USERID: LISTSERV  DATE: 04/01/94 - 04/07/94    LISTSERV 1.7f
 
       Connect Time      :       165:37:09    hh:mm:ss
       Virtual CPU       :       587:37.95    mm:ss.ss
       Overhead CPU      :        63:10.67    mm:ss.ss
       Paging            :         755,380    Pages
       Spooled I/O       :       6,695,151    Records
       Non-Spooled I/O   :       9,159,944    SIOs
 
  USERID: LISTSERV  DATE: 04/15/94 - 04/21/94    LISTSERV 1.8a
 
       Connect Time      :       167:59:46    hh:mm:ss
       Virtual CPU       :       396:08.70    mm:ss.ss
       Overhead CPU      :        53:10.26    mm:ss.ss
       Paging            :         650,331    Pages
       Spooled I/O       :       6,750,960    Records
       Non-Spooled I/O   :       6,765,362    SIOs