Client Performance Issues

Good evening:

We recently moved off of an older model AS/400 to a new iSeries. In the
move, we upgraded Domino from R5.0.11 to Domino 6.5.1. We have T-1
connections to our remote office (California). There are no applications
on the Domino server, it is strictly mail. Since the upgrade, all I have
heard is how slow Notes is now. I have to admit that it is slow. It
probably takes a good minute to open a mail file, to switch views, open
the calendar view, etc. Being a "smart" guy, I just replicated my mail
locally so when people call, I can say that I don't see it (LOL! - I
think that is a Dilbert-ism). Any way, I digress.

OS/400 V5R2
Domino 6.5.1 (only one partition on the iSeries)

To make this even more fun, the IT Manager thinks it is because we also
installed Trend's Anti Virus software on the server (V2 Release 5 Mod
0). I don't think so . . . I think that I may have *Base pool set too
low. Would that cause the Notes clients (all 6.5.1) to really slow down
during database operations in Domino? I have no problem turning on
performance adjustment and checking. But before I do, I figured that I
would ask for esteemed group's opinion.

Thanks.

Gregg