Extremely slow SLA recalculation time when a Service Desk project contains a high number of issues

Issue description

When a Service Desk project contains a high number of issues (for example more than 20k), the SLA recalculation might get stuck or take a long time after editing an SLA configuration.

Steps to reproduce

• Create a Service Desk project with at least 20k open issues
• Make a change to an existing SLA in the project via the page Project Settings > SLAs, in order to trigger the re-calculation of this SLA for the entire project

 Note that this issue has not been reproduced on Atlassian side, but it has been reported by some customers.

Actual Result

The SLA recalculation takes a lot of time to complete, and from the UI it looks like it's stuck since the progression bar does not seem to progress.
Note that the time it takes for the recalculation to complete varies depending:

• on the customer's environment
• the length of the history of issues for which the SLA needs to be recalculated
• the number of goals in the SLA configuration
• the number of SLAs configured in the project

Expected Result

The recalculation of the SLA should be faster (although it is difficult to tell how long it should take as it depends on many factors, see above).

Workaround

No known workaround.