if performance is a higher requirement than functionality
It's neither a "higher" requirement, nor a "lower" requirement. Performance is always
a requirement. In the end, someone or something is waiting for the results, and they aren't going to wait forever. Now, where the balance lies between performance and functionality, that depends on a case-by-case bases. I don't think the blanket statements made by the OP reflect any real world scenarios (which surprise me, as petdance usually comes across as someone with both feet in the business world).
Likewise you can introduce unnecessary architectural complexity if you optimize before finishing any functional requirements.
Or the other way around. ;-) I guess most of us have encountered systems that were beautifully designed, and has implemented every little aspect that was dreamed up before hand, but noone uses it because performance was factored in too late.