I have a similar situation but slightly different:
I have a datasource that loads a list of items for a dropdownlist. I then have a dropdownlist that is constructed on the fly in an editor function for a grid column. Each time I activate the editor, the datasource makes an ajax request to the server to load the data for the dropdownlist. I tried adding the autoBind=false attribute to the editor (see code below) but it STILL makes an ajax call to the server to reload the data for the dropdownlist. I want to be able to load the data source once and not have it reload on each activation of the editor but the autoBind does not seem to work in my case.
$('<input data-text-field="displayfield" data-value-field="valuefield" data-bind="value:' + options.field + '"/>')