You do not mention which version of db2, what O.S. and how many spindles you have. So is 1.000.000 inserts in 7 minutes good or bad? Dunno. If your table would NOT have any indexes at all you're observation could be odd. So please give us more info about the table and the indexes. Also which columns are updated and are those columns used in 1 or more indexes.
And you procedure, does it fire 1.000.000 time an insert of adding 1 row? Or 1.000 inserts adding 1.000 rows at the time? Any commits in between?
Please answer this questions and then, maybe, we can tell you what is happening.