The testcase which is attached at CR 6348045 runs much slower on Java SE 6 than on J2SE 5.

$ java -showversion PerformanceTest
java version "1.5.0_10"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_10-b03)
Java HotSpot(TM) Server VM (build 1.5.0_10-b03, mixed mode)

Time needed for copy the archive :154626 ms

$ java -showversion PerformanceTest
java version "1.6.0"
Java(TM) SE Runtime Environment (build 1.6.0-b105)
Java HotSpot(TM) Server VM (build 1.6.0-b105, mixed mode)

Time needed for copy the archive :532257 ms

hprof output from JDK 5u10:
rank self accum count trace method
   1 72.13% 72.13% 6261 300060 java.util.zip.Deflater.deflateBytes
   2 15.39% 87.52% 1336 300067 java.util.zip.CRC32.updateBytes
   3 2.09% 89.61% 181 300069 java.util.zip.Deflater.deflateBytes
   4 1.38% 90.99% 120 300066 PerformanceTest.startTest

hprof output from JDK 6:
rank self accum count trace method
   1 57.52% 57.52% 14852 300056 java.util.zip.ZipFile.read
   2 31.27% 88.79% 8074 300054 java.util.zip.Deflater.deflateBytes
   3 6.71% 95.50% 1733 300053 java.util.zip.CRC32.updateBytes
   4 0.62% 96.12% 160 300067 java.util.zip.Deflater.deflateBytes
   5 0.34% 96.46% 89 300060 java.util.zip.DeflaterOutputStream.deflate
   6 0.34% 96.80% 88 300063 PerformanceTest.startTest