Performance degration after release of 4.12.4

Performance degration after release of 4.12.4. With this release, there was an update to how Xray retrieves data from Jira.
This was because the way Xray communicated with Jira to retrieve issues became deprecated. The new API provided by Atlassian is more restrictive and it means that retrieving issues might imply more requests which makes it slower, this is more noticeable as later pages of issues are retrieved, which is what you are experiencing.