Rank field causes performance issue when cloning an issue in JIRA

The rank custom field can cause significant performance issues when cloning an issue in JIRA. Looking at the source it looks like cloning an issue can cause a full reindex of all issues in that project to reassign rank values in the rank custom field provided by Greenhopper. For projects wit lots of issues (100000+) this can cause JIRA to spin for a long time.