I'd hardly call the 'back-enda' of sbcl or cmucl 'swiss cheese'. We don't know the cause of the problem we're encountering with deliverator on sbcl/cmu, or we'd have fixed it or gotten the sbcl devs to (depending on where the problem is), rather than assigning blame and switching platforms. The problem, in a nutshell, is that *something* isn't getting garbage collected despite the fact that we can