Issue Summary

On Jira Software projects, team-managed or company-managed, if you set the Group By field on the Board to an option ( like Epics or Assignee ) and it creates a large number of swimlanes ( > 140 from testing ), it will cause the page to take a long time to complete loading and an error is seen that the page is unresponsive.

Steps to Reproduce

1. Create a team-managed or company-managed Software project
2. Create a large number of epics ( More than 150 ) and create some tasks under the epics to display on the board
3. Set the Group by field on the board to group by Epics
4. This will create a large number of swimlanes as each issue will be grouped under its own Epic
5. Reload the page and wait for the error to appear

Expected Results

The board loads as per normal and swimlanes/issues are displayed

Actual Results

The page continues to load for a long time and eventually, a page unresponsive error is displayed by the browser.

Workaround

The only option is to either set the Group by to "None" or use another option that creates fewer swimlanes