'Epic Link' column causes longer load time for Jira Issue Macro

Summary

Jira Issue Table with 'Epic Link' column will take much longer to render compared to a table that doesn't have 'Epic Link' column in it.

Environment

Tested on Confluence 6.8 + Jira Software 7.8

Steps to Replicate

1. Create a test project in Jira (eg. TEST)
2. Create ~1000 Jira Issue in Jira with Epic Link in TEST
3. In Confluence, insert a Jira Issue Macro with project=TEST as the search filter
4. Include "Epic Link" in the Columns to display option
5. Set Maximum issues to 1000
6. Insert
7. Observe the amount of time taken to load the table
8. Edit the Jira Issue Macro and remove "Epic Link" in the Columns to display option (leave the rest as it is)
9. Insert
10. Observe the amount of time taken to load the table again

Expected Behavior

The table loads quickly with or without "Epic Link" column

Actual Behavior

According to test results, it took ~2 seconds for the table to populate without Epic Link. On the other hand, it took ~15 seconds for the table to populate with Epic Link.

Condition	Load Time	HAR File
With "Epic Link"	~15 seconds	with epic link.har
Without "Epic Link"	~2 seconds	without epic link.har

Note

• Jira Issue Macro starts showing notable slowness while Maximum issues is set to 500 or above.
• If Confluence took longer than the expected timeframe, you'll notice the following message:
  
• The same issue is also observed when 'Epic Name' column is added to the filter as well.

Workaround

• Increase socket timeout as suggested in Timeouts in the JIRA Issues Macro or Highlighting Plugin
• Lower the amount of issue display in the table.