Oracle Support has produced a very complete item import performance improvement metalink note. If you have access to Oracle Support, then you can look up the note 1208945.1.
This note is especially appropriate if you are using any type of item import process with PIM Data Hub even WebADI use.
There is sql scripts to run to improve performance as well as patches to apply that are reported to produce greater performance.
If you are currently in your implementation then I am going to direct you to another of my articles where one of my good buddies at Oracle Support has shown me how to look for PIM patches.
FYI: apologies if you were directed to this article yesterday but there was no content. I published instead of simply saving my draft.
- Importing Metadata into PIM Data Hub 12.1.3 (mckinleyalexandra.wordpress.com)
- Where is PIMDH R12.PLM_PF.C and when is it going to be released? (mckinleyalexandra.wordpress.com)