And I'm sure if you said that to the CTO they wouldn't take offence and would react in a rational, measured way. Actually, I've worked with managers that would

And I'm sure if you said that to the CTO they wouldn't take offence and would react in a rational, measured way. Actually, I've worked with managers that would react OK to that, and ones that definitely wouldn't, but I wouldn't tell any of them their work wasn't "properly engineered". Stick to the objective facts: this version runs much faster (no need to even mention the 'several orders of magnitude' factor unless they really want to know).