Actors performance versus traditional Java threading

Sorry about maybe reentering an old-patched issue but i was reading about Actor pattern performance of Scala not been there yet for compete against classical java Threading model.. 
is this a JVM design issue (been primarily a java perspective Vm) ?
as Actor pattern is without a doubt a superior pattern against java threading model.. how to get there?  
is this continues to be true?
Thanks in advance,
Fabio Kaminski