Everyone is trying to help, it is just difficult to give a real answer without being able to reproduce the issue.  If you have lost the source code for this, I think you are basically finished in your quest to find a reason.

As far as everyone trying to help you with optimization and your process itself, think of it like this.  If you took your car in to get your brakes replaced and the mechanic did not tell you that you had a bad tie rod end, wouldn't you be pissed when your steering failed a couple of days later?

Please don't get frustrated and fault people for trying to help.