First, check to see that you meet the minimum requirements for ASEBA-Network: http://aseba-network.aseba.org/
Next, check to see how large your directories are. For example, if your directory contains more than 400 people, you will experience a slower load time when trying to access it.
It is recommended that you have fewer than 400 assessed persons per directory. You could create many directories by "A, B, C..." and put all the assessed persons with last name starting with "a" in the "A" directory, etc.