Woof. JIRA is so slow, and managers never seemed to set it up correctly. I have trauma from using it!
1. All the checks it has to do to see if there are relations between tickets, states, triggers, actions, reports, etc.
2. Accessing separate subsets of data for each ticket from different locations and bringing it all together (epics, sprints, user lists, comments, reactions, linked issues, linked PRs and branches, etc)
3. The code is apparently a complete dumpster fire, from what I've heard from people at Atlassian.