I've done some more testing and here are the results:
1. change raid controller drivesettings from cached I/O to Direct I/O
2. delete all targets and create them new using File I/O
3. delete the bonding

here is the hdparm:

*-----------------------------------------------------------------------------*
hdparm -t /dev/sdb
*-----------------------------------------------------------------------------*
/dev/sdb:
Timing buffered disk reads: 844 MB in 3.01 seconds = 280.80 MB/sec
*-----------------------------------------------------------------------------*
hdparm -t /dev/sdc
*-----------------------------------------------------------------------------*
/dev/sdc:
Timing buffered disk reads: 800 MB in 3.00 seconds = 266.25 MB/sec
*-----------------------------------------------------------------------------*
hdparm -t /dev/sdd
*-----------------------------------------------------------------------------*
/dev/sdd:
Timing buffered disk reads: 822 MB in 3.00 seconds = 273.76 MB/sec

Is there anything else i can do to speed up my system?

What about the tuning options in open-e? I've read that there can be done by changing some parameters.