Are you performing compressed dumps? What compression level are you using?
Compressed dumps can require a good bit more cpu than uncompressed dumps (the amount of cpu resources depends on the compression level), so make sure you're not maxing out your cpu resources on the replicate dataserver host.
If you are using compressed dumps on for the replicate dataserver ... what happens if you a) reduce the number of stripes or b) disable use of compression?
I'd also have your system/SAN folks monitor your disk throughput on the two hosts. [Objective is to see if you've got 'slower' disks on the replicate dataserver's host.]