Because they don't care about performances. They just want you to not pirate the game for the first couple weeks after release so they can make the most sales money, then once the crack is out, they remove Denuvo...or not.
The security is for their benefit not yours, so they don't have a reason to trust your hardware over proprietary software they control.
But maybe I'm wrong, I'm just assuming. I'm not a dickhead using Denuvo.
I don't think the people who want to speed are the kind of people I want driving anyway.
Admitting you want to bypass the rules should be a red flag and imo warrant an immediate cancellation of your permit. You're driving a thousand kilos of metal at bone shattering speeds, if you can't be trusted to be responsible, don't drive. (And it's a general you, not you OP)
Also statistically, on the amount of monkeys that do not write Hamlet to the letter. There is an insane amount that missed it by a single letter, or punctuation sign.
How come you have a headache every morning ? Sounds pretty worrying to me.