How do I troubleshoot performance problems with an Oracle SQL statement

Question

I have two insert statements, almost exactly the same, which run in two different schemas on the same Oracle instance. What the insert statement looks like doesn\'t matter - I\'

Answer 1

I've put up my general list of things to check to improve performance as an answer to another question:

Favourite performance tuning tricks

... It might be helpful as a checklist, even though it's not Oracle-specific.