Hello Community,
For me, this is one of the least defined topics as I have not had experience and frankly, there is no unified go to approach yet.
In recent JIRA Versions, as far as I know there is no such "limit" which cannot be breaked and I know that optimization is much more efficient than total issue number.
Having said that, there will be a near time for me , where the need for archiving would arrive.
Current instance stats:

"Archived" Projects, which generally I have mapped to a permission scheme, accessible only for audit and reporting users, are a good thing, but still all issues are loaded in lucene indexes.
Partial indexing of issues would be a good improvement, but I don't think it would be the only one needed as I'm sure the performance stretches further than just indexes.
I would like to get your feedback on:
Which is your favorite Archiving Policy, assuming you have one ?
Do you have any go to strategies for better "archive" optimizations?
Best Regards