v11 performance

I'm running v11.10.fc2 on Aix 5.3, IBM Squadron ... I have a script that builds indexes on several fragmented tables. Each quarter we drop the indexes, drop the oldest four fragments, create the next four fragments, and then rebuilds the indexes. In the past using v10.fc6 on the exact hardware these scripts have finished in about 1.5 hours. Running them for the first time on v11 they ran for about 7 hours... All that to ask if anyone else has experienced this sort of degradation in index build performance... One thing that has changed is our storage backbone .. and that is where I believe the problem might be, but I need ammunition ..... Any info would be greatly appreciated. Peter