Finite records in bindonload

I need to have a combo box display data based on the selection of another combo box. Specifically I have a Parts table and I need the part description to show on its own field when the part is selected. I have used bindonload.

Here is my code:

<th>Part Number</th><td><cfselect name="PartID" bind="cfc:dfSources.getPart()" bindonload="true" />  </td>   
<th>Description&nbsp</th><cfselect name="Description" bind="cfc:dfSources.getPartDescription({PartID})" /></td>

This works very well for a few records - just about 300. After 400 records it is slow, and upwards of 500 it does not work.

Is there a limit to the number of records a bind can return?