In the file:
./apache-openjpa-2.1.0-source/openjpa-lib/src/main/java/org/apache/openjpa/lib/meta/ZipStreamMetaDataIterator.java line : 119
The buffer size is fixed as 1024 bytes. With the size of the data varies, the performance can be damaged a lot.
We need an appropriate buffer size which depends on the size of the data to be copied.
This is the same as the Appache Bug (https://issues.apache.org/bugzilla/show_bug.cgi?id=32546)