Right. I don't think we have measured the performance recently so I cannot comment off the top of my head, but at the same time I cannot think of a reason for why it would have changed.
Sounds like recycling is still worthwhile, even though the current user space libraries don't do so. I'm not super familiar with them -- is that due to a design limitation (not using slabs?) or just work not done?
What's the cost of keeping it? Is there a burden on maintenance (particularly with new stuff landing) or re-verification?