IMHO, you should not reply to the whole group about who really d

Instead, you can mention what you also did to make it better. Then people will add up your both efforts. For front office staff, they don't really care who actually did it in the back. And you're not exposing your relatively internal problems to outside to embarrass your boss or big boss. As a DBA, this kind of performance tuning work happens quite often. In a long run, people know who's the top gun.