Starting with version 4.1.1, Power Scripts™ is able to cache the results for the expressions used to filter issues, either built-in or user provided. This feature can greatly improve performance as well as degrade it, so use it with extreme care.
Reasons to use these features:
You have saved filters and users are performing the same JQL queries over and over again.
You have plenty of free memory and CPU.
Reasons not to use these features:
You do not have enough free memory.
CPU is constrained.
Your users are performing ad-hoc queries.
Index is maintained automatically for now, and its parameters are not editable. If enabled, the engine will auto-determine whether an expression is used frequently and will trigger a reindex on the respective script. While indexing, the index will not be available, but once completed, it will find issues extremely very fast.
Feature is cluster aware, and it should work without problems in clustered environments as well.
To enable it, visit the JQL configuration page, and click the Enable Fragment Index button.