“Replace jira-users with the ‘Anyone’ permission — Thanks to Jamie Echlin for this tip. Permission checks are expensive, especially for any JIRA issues with hundreds or thousands of links, such as GreenHopper epics.”
Note that this tip is only possible with instances in which there is no anonymous access allowed or for which there is no difference between users in the jira-users group and anonymous users (at least for some permissions). See Managing Project Permissions.
IMPORTANT NOTE: If your instance is in Internet, this solution is not good because when the group Anyone is in BROWSE issues permission, anyone, logged or not in the JIRA can see the issues!!!!!
BE CAREFUL IN PRODUCTION ENVIRONMENTS!!!!!!!
The best solution is minimize in BROWSE permission the number of groups and members in the groups.