You should realize that most of the CPU performance increases of the last 10 years depend on technology that is disabled in Qubes OS by default for security reasons (speculative execution). Also that most CPUs, most of the time sit around idle waiting for input. So moving that data quickly (or not at all) is advantageous. Hence you might be better off spending your money on a high performance, high quality SSD (they are NOT all the same by a long shot!) and buying as much RAM as you possibly can. Finally, temperature/cooling has effects on CPU performance too and is worth looking into.
laptops that are “privacy-ready” that somehow you are safe?
The idea here is that you can detect tampering. If you don’t trust those companies (something I have a lot of understanding for) then build your laptop yourself. Inspect the hardware yourself, build and flash coreboot/heads yourself. Perfect? No, but as good as it gets for now.
“it depends what your threat model is”
As you concluded: there is no absolute security. Rather the more countermeasures/detection you want to have in place the more expensive (not only money, but also effort/attention/learning) it gets. You could spend your whole life worrying about security 24 hours a day and do nothing else. But you wouldn’t get much done. How much effort are you prepared to put in to defend against what?
If nation states and three letter agencies are part of your threat model, you will have to do a lot: do not use phones of any kind, never sleep in the same place twice, only use cash, avoid public places/ATMs/toll roads, change your appearance daily, don’t make friends, don’t stay in the same place for long, never get drunk, never relax, never trust anyone … sounds fun – right?
Hence a lot of us, who are fortunate enough to be of no substantial interest to the aforementioned entities have made the decision to consider them “residual risk”. The things I actively worry about are mostly my own stupidity, criminals, script kiddies and some low-level forms of corporate espionage. I also try to avoid warrant-less mass surveillance and surveillance capitalism to a reasonable degree.
Your situation may vary. If you fight for human/animal rights and against suppressive regimes or corporations I wish you all the best. If you are just looking to not pay for your entertainment or engage in substance or other forms of abuse … not so much. I might actually root for the other guys then