Message9376

So the additional overhead here has a simple root cause: unlike CPython, Jython uses the same method, PyArray.fromStream, to read from an input stream into a given array. Although the read should be reasonably fast/inlineable (but more overhead than simply looping through the string), the write performance into the array is very slow since it uses java.lang.reflect.Array, in this case java.lang.reflect.Array#setByte.

Some simple specialization would speed things up considerably, much as was done with CPython.

Changing misleading title! (Copy-on-write would still be interesting, and perhaps more feasible on Jython.)