Percona 5.5 and 5.6 performance.

I have created two identicals VMs to test percona.
Both with CentOS 6.5 64bits, 2 vCPU and 1GB of memory

I used sysbench to do a test and get the result bellow (transactions per second)
Both database populated with the same command.

sysbench --db-driver=mysql --test=oltp --mysql-table-engine=innodb --oltp-table-size=1000000 --mysql-socket=/var/lib/mysql/mysql.sock --mysql-user=root --mysql-password=123456 prepare

Percona-Server-server-55-5.5.36-rel34.1.el6.x86_64

for i in $(seq 1 5); do echo $(date “+%Y-%m-%d %H:%M:%S”) " " $(sysbench --db-driver=mysql --num-threads=32 --max-requests=100000 --test=oltp --oltp-table-size=1000000 --mysql-socket=/var/lib/mysql/mysql.sock --oltp-read-only --mysql-user=root --mysql-password=123456 run | grep transactions: | cut -f2 -d’(’ | cut -f1 -d’ '); sleep 10; done
2014-03-25 11:27:07 2368.71 per sec.
2014-03-25 11:28:00 2465.49 per sec.
2014-03-25 11:28:51 2497.78 per sec.
2014-03-25 11:29:42 2442.25 per sec.
2014-03-25 11:30:33 2445.34 per sec.

Percona-Server-server-56-5.6.16-rel64.2.el6.x86_64

for i in $(seq 1 5); do echo $(date “+%Y-%m-%d %H:%M:%S”) " " $(sysbench --db-driver=mysql --num-threads=32 --max-requests=100000 --test=oltp --oltp-table-size=1000000 --mysql-socket=/var/lib/mysql/mysql.sock --oltp-read-only --mysql-user=root --mysql-password=123456 run | grep transactions: | cut -f2 -d’(’ | cut -f1 -d’ '); sleep 10; done
2014-03-25 11:44:48 2005.92 per sec.
2014-03-25 11:45:48 2035.94 per sec.
2014-03-25 11:46:48 2041.90 per sec.
2014-03-25 11:47:47 2035.28 per sec.
2014-03-25 11:48:47 2037.31 per sec.

The file /etc/my.cnf is the same.

Why the new version is worst than older?

yes it is true based on feedback on several forums and from my benchmark results that old version 5.5 still winner over new 5.6. this is case for MySQL Community Edition and Percona versions.
see http://mysqlyogi.blogspot.in/2013/04/is-mysql-56-slower-than-55.html
http://www.percona.com/forums/questions-discussions/mysql-and-percona-server/7800-mysql-5-5-vs-5-6-performance
Even latest minor version release 5.6.16 has no performance boost. Why MySQL 5.6 is slower ? still no answer.