From 1993-1996 I worked with an AS/400. This was before they started putting in PowerPC chips in them. It ran very slow, and the Showcase ODBC we used to connect up with the database on the AS/400 was slow. All I did was the Client Access/400 software install, and the database to make sure that the Network Administrator did not assign two virtual terminals the same session ID codes.
We migrated databases from the AS/400 to a SQL Server running under NT 3.1 and it was much faster. The poor AS/400 had a ton of other users giving it requests and I think a whole bunch of RPG, COBOL, FORTAN, and PL/1 programs running on it, taking up processor time. Many of which were converted to the AS/400 from an old IBM 4381 Mainframe that we happened to get rid of by hiring consultants to quickly port those programs to the AS/400 environment.
Piror to the PowerPC upgrades to the AS/400, from what I saw, the AS/400 was very very slow. I assume that the PowerPC upgrades have speed things up now?