Submitted through bugzilla:

RenderBuffer copied array contents to the RenderBuffer's Unsafe using a native
method, small copies were done using a copy-loop written in Java.

This patch makes use of Unsafe.copyMemory instead of the native method, which
has been introduced with JDK7b36, and should offer the same performance as
System.arraycopy.

Accoring to Alan Bateman this new method is used for >6 elements by NIO too,
however I am not sure if this check still makes sence - I guess Java2D only
very seldom copies arrays < 6 elements to the Unsafe, and in those cases the
other pipeline overhead most likely reduces the copyMemory overhead to noise.
With removing it we could get rid of some code ... and a conditional :)