Hello Steve

I don't know why commit=y should improve performance either, but I believe that there is an exception to this rule. When importing LONG,LOB,BFILE,REF,ROWID or type columns array inserts aren't done, so a commit is performed after each row. They say that for tables with these kind of columns it is preferable to set commit=n (and hope your rollback segments are big enough!). I'm going to be working on similar project to yours this week, and i'm going to benchmark LONG column imports with commit=y and commit=n. I'll let you know what I find out.

Also, you might find this free tool of interest (I've not used it myself):

http://pepi.sourceforge.net/#who