I don't think "work as intended" is an accurate description – I don't think the intention of enabling CDI by default is to introduce a 30% performance regression in EJB operations.
We need to look into and optimize the Weld implementation here. If we conclude that it cannot be improved on, then we can figure out next steps. But I suspect, given the size of the penalty, that there is some optimizing we can do. I'll get PSR staff to do some initial analysis (but also, can we check with the Weld implementors and see if they are aware of this, as they were already aware of the memory leak)?