I've tried several things to eliminate the one-minute to
one-and-a-half-minute delay LISTSERV is experiencing in sending messages to
a list, but it's still there.

I am running Diskeeper on the server.  I disabled that.

In the Site Config program, under "Optomize for...", I selected "Other" in
the section labeled "Type of delivery system", since our SMTP server is a
VMS system running PMDF, not a Unix system or a system running LSMTP.

I removed the postmaster account from the site maintainer list and replaced
it with a ListMgr account, in case the loop checking was delaying things.

I've tried stopping and restarting both LSMTP and LISTSERV.

I'm not sure what else to try.  Does anyone have any other suggestions?