The add-on can have a significant impact on JIRA performance if it isn't configured to match your JIRA instance and add-on usage.

JIRA indexes all issues in order to enable fast and precise searches. This means that an Issue must be reindexed each time a field, e.g. a custom field, is updated.
Performing an issue reindex consumes quite a lot of CPU time.

A single issue will in most JIRA installations usually reindex within less than a second or two. However, reindexing hundreds, or maybe even thousands of issues will take quite a long time with the CPU usage going to the roof.
Though optionally, the add-on makes heavy use of custom fields and therefore must perform regular issue reindexing in order to enable reliable issue searching.
One can configure how aggressive the issue reindexing should be carried out. If you experience performance issues, you should configure a less aggressive strategy. On the other hand, if you want reliable searches and always updated issues, you should go all in.

Attributes

Use

The Scheduler Interval defines how often SLA Values will be updated for all issues included in a SLA Search.

If you have 20 SLA Searches JIRA will perform 20 searches every configured minute (in this case every 10 minutes)

and then update all issues included in the searches.

Re-Index policy:

One can configure different re-index policies.

Next - SLA Queues

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