Hello Henry,
this doesn't surprise me at all. It is doing exactly "what it says on the tin". We usually use just the personal server on our PCs. The only time I've needed to use the network server is when testing replication, and 3 connections are more than adequate.
If you want to do load testing your can either put the load through the 3 connections (have the database itself spawn queries) or get a full version of the server. To do this you can buy it as normal or maybe talk to someone at SAP (or a 3rd party vendor) about an evaluation.
Plainly, if you've reached the point of doing load testing, your project has already made the decision to use SQL Anywhere*. It's time to add some 'real' copies to the project budget.
Paul
*good pick 