The Zorin bros should stick with what they know. If your comparing a modern computer running Zorin OS Core, and a second exact same computer running Windows 11, with all the invasive recall and everything else slowing it down, well yeah, the computer running Zorin OS will come out on top, thats basic science testing there.
If we compare Linux based on Zorin OS XFCE Lite, to Windows 11, XFCE will come out on top, at biblical benchmark levels in comparison. But, if your trying to say that Zorin OS 18 Core, is going to speed up a 15 to 20 year old computer, sorry, the science is not there to back up such claims, because the hardware is too old, and has less to do with what software runs on it.
What we see with Linux, as new Linux distro versions come out, while they don't require premium top end hardware, they do run better on modern computers. And light versions of Linux, can run ok on 10 year old hardware.
With each new version of Windows however, they always required modern era computers, due to high level system requirements. In the 90's, most computers ran either Win95 or Win98. When WinXP came out, it couldn't run on 90's computers, due to those higher system requirements.
Same when Win7 came out, forget your XP machine, you better have had a machine from the late 2000's to run Win7, or forget it. As I said, Windows has always been a resource hog, but never as intense as Win11. Most gamers who are on that OS, state the OS is using 30% of their CPU. They often state, if they were not using top of the line 8Core - 12Core CPU's, they would have no headroom for gaming at all.
So, with that said, if I were the Zorin bros, my recommendation, is to state, using modern computers, Zorin OS will speed up your computer performance, as compared to an equal machine, running Win11.