Hi Suman,
I've discovered, using this document:
that I have two dimensions with a high ratio percentage. I've marked them as High Cardinality as I cannot create them now as Line Item Dimension (it'll be a mess and too much work to do it now).
Marking them as High Cardinality didn't solve the problem.
I think problem would be solve if dimensions are Line Item Detail, but as load is Delta, I'm not going to modify infocube so far.
Thanks a lot for your help.