"Promoting diversity" only equates to "sacrificing performance" if you accept the premise that white men are by default the most qualified for everything. Or maybe to be slightly more generous, the premise is that the prior state of affairs where mostly white men were being hired was colorblind and based on merit, so anything else must be sacrificing merit based hiring.

I see no reason to buy that framing though and plenty of reason to think it's bunk. Even liberals can fall into the trap though, because policies to promote diversity are explicitly stated while it's been a bit (although not all that long in the grand scheme of things) since the biases that can lead to prioritizing white men are actually written down. That's how the "tradeoff" ends up in things like the FAA slides. It's unclear what factual support that slide had, but clearly the author just took it as a given, as do a lot of other people.