Summary

Switching workflow scheme on a project takes forever or breaks if there are too many issue types

Steps to Reproduce

1. Have (or create) a big number of issue types ( > 200 ).
2. Open any project, open settings.
3. Select "Workflow" from the left hand side panel, click on "Switch Scheme" button on the right hand side.
4. Select alternative scheme, follow wizard instructions.

Expected Results

The workflow is changed in a reasonable time frame.

Actual Results

The workflow switch takes a very long time or breaks entirely

Notes

All individual issue types on the instance are checked rather than just the ones applicable to the given project
Also, it would seem that the same select (executed times (<num of issue types> * <num of projects>)) is run on every one of the 3 steps involved in the wizard. The first run is very expensive (and unless there's any caching on the DB side, so are the following 2).
Further notes here

Workaround

• Reduce the number of issue types (not a good workaround, but that's the only viable option at the moment).
• Try to optimize SQL tables (review indexes etc. to speed up overall ETA)