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?