Resolution

• JIRA now uses the extension of the file to determine if it is a zip, instead of opening and inspecting the top of the file.
• If it is a zip, the description of the entries is cached so the zip doesn't need to be opened again.

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Steps to reproduce:

1. Create an issue and reload it a few times; observe the page load times on average.
2. Create a zip file with about 10 files at the root.
3. Attatch it to an issue 10-20 times.
4. Refresh the issue and now observe the average page load times.

The problem is that the jira-view-issue-plugin extracts every single Zip File attached to an issue on every page load. See: jira-components/jira-plugins/jira-view-issue-plugin/src/main/resources/viewissue/attachmentsblock.vm

This should be turned into an asynchronous operation so that, only when a user clicks on the drop-down arrow for that attachment do we fire a rest call and get the data, performing the extraction in that operation.

In the long term we should even consider Connecting that location for Cloud so that we can pull zip file extraction out into a shared service.