The 'Plan to clone from' drop-down inside the 'Clone job' page is slow to open

Issue Summary

The Plan to clone from drop-down button inside the 'Create > Clone plan' page takes a very long time to open for large Bamboo deployments. Times ranging from 25s to 60s were observed when trying to open the drop-down.

Steps to Reproduce

1. Access Bamboo from a web browser (e.g. Firefox).
2. Access the Plan configuration page from one of the plans.
3. Click the 'Add job > Clone an existing job' button under one of your stages.
4. Click the Plan to clone from drop-down button to search for a plan.

Expected Results

The Plan to clone from drop-down loads in a couple of seconds at max and we can start looking for a plan to clone.

Actual Results

The Plan to clone from drop-down takes a really long time to finish loading. This is related to the fact that we try to display a list of all plans a certain user has access to in the drop-down. The more plans you have access to the more time it takes to load the drop-down.

Workaround

1. Use Bamboo Specs to manage your plans (this way you can easily clone/copy tasks from other plans into your Specs code).
2. Try using different web browsers. It won't solve the problem but may present different loading times.