LSI 150-4 slow after CentOS 5 upgrade

Hi All,

I am running Cent OS 5 (Red Hat Enterprise Linux 5 clone).
My RAID card is an LSI 150-4, bios 713R G121.
My kernel is kernel-2.6.18-8.1.1.el5

I just did a clean (reformat) install on
a server. The former OS was Cent OS 4.4.
No hardware was changed out or added.

Problem: my file I/O is now 3 times slower
A fuil backup under 4.4 took 1:05 hours, whereas
5.0 takes 3:15 hours. (4.4's backup files
is even slightly larger than 5.0's)

Do anyone have any suggestions as to how to get
my performance back, other than downgrading to 4.4?
Is there a special 5.0 scsi driver I can use?

Many thanks,
--T

.