Asynch Descriptor Resize explanation
Just so there is some sort of answer to this, here is some information I have found.

On MOS there is a document called "High Numbers of 'Asynch Descriptor Resize' Wait Events Seen" (Doc ID 1273748.1)  This seems to indicate that the problem is really another wait event slowing the system down and in turn causing these, so they aren't really the source wait event.

Oracle-L has a thread on the wait event, but no mention of it on Windows.

OakTable has some interesting info on the problem, and says, 


  ...the resize apparently sucks on Linux. Perhaps that’s why other ports also suffer and have seen the same wait event.