Using JIRA Enterprise Edition, Version: 4.0.0-Beta2-#432 at http://jira.atlassian.com today, I saved a filter that gets all issues in the JIRA project. I then went to my dashboard and tried to add a new gadget to show the statistics of that filter, grouped by reporter, sorted by total and in descending order.

Firefox absolutely hung waiting for a response. This behaviour was repeatable. Attached is the report sent to Apple in the hope that it may point to the problem.