I checked the logs and noticed that there is a drive that is coming back with the Unexpected Sense errors:
Event Description: Unexpected sense: PD 09(e0xfc/s2) Path 4433221101000000, CDB: 00 00 00 00 00 00, Sense: 2/04/02
This indicates that the drive is not ready. I could not find any other entry that would explain why such performance impacts after the firmware upgrade. I noticed some entries saying “Event Description: Controller cache discarded due to memory/battery problems” with the previous firmware release.
How is it that you are measuring the performance of the drives?
Do you have an update as to how you are measuring the RAID performance? The more details you can provide on this, the better for the diagnostics and investigation.