Facing slowness issue while clicking an issue from Filter search or Rich Filter Query

[Jayabalaji B V]

While trying to open an issue from a Filter search or Rich Filter query, some issue are loading very slow and some issues are timing out and getting an error message "PRJ-XXXX can not be opened. The issue may have been deleted or you might not have permission to see the issue." 

While opening the issue in new tab from the filter search, the issue is loading without any delay. So we are facing slowness only when we are opening issue directly in the same window as in where the Filter search results are returned.

Also once the issue gets loaded with the delay of 15-20s, and later if we go back and try to open the same issue again then it loads within ms without any delay

As per our analysis till now we have found out it may be due to below pointers.

• This issue is not affecting all projects. Its only affecting the projects which is using a particular custom field or may be a group of custom fields.
• When we tried to replicate the issue with developer tools on in Chrome, its taking around 15-20s to load "AjaxIssueAction!default.jspa" where as for other issue they are loading within ms.
• When we tried to replicate the issue in Jira "Safe-Mode", we didnt find slowness while script runner plugin is disabled and while enabling it again the slowness reoccurred. But we couldn't find the root cause since we haven't had changes to the scripts for a long time.

It would be helpful if someone let us know how to troubleshoot this kind of issue to find the root cause