[Etoys] Performance improvements form 3.9 (backported) #3

[Yoshiki Ohshima]

  Scott,

> I've pushed an update to olpc that fixes the two bugs I know of that  
> appeared in Quadrangle as a consequence of update 1074, so I mention  
> the issue here only as a cautionary tale.  Partial backports can be  
> dangerous, sometimes in quite obscure ways...

  Thanks!

> (2)  I have reservations about the SubMorphCopy change-set  
> (1075SubMorphCopy-md).

  Hmm.  We can revert this.  Array>>copy is two times faster, it
will offset this.  After B-test, we can get it in again.

-- Yoshiki