Reproduction Notes:

• Insert the JIRA Issues macro
• Paste the XML URL to a search
• Customize the fields to return by specifying a custom field

In my example, I'm requesting: summary, type, updated, goals

It generates a request like this to JIRA:

        Request URL Parameters :
                tempMax=1000
                field=summary
                field=type
                field=updated
                field=allcustom
                field=goals
                field=link

I don't think the field allcustom should be there. We're grabbing all available custom fields which makes the search extremely slow on instances with many custom fields.