How are you handling commits? I think "autocommit" is turned on by default (commit after every execution of an insert or update), and that can be outrageously slow when slogging through a long list.

I wrote a general-purpose command-line tool for doing inserts/updates using data from stdin or a file, and the best thing about it is the option that lets me set the commit interval. If I forget to use that option on an input of many thousands of rows, I really regret it, but when I set it to commit every 500 or 1000 rows, it flies, and I love it.