The MacBook Pro Turbo Boost throttles, ie. if you run the CPU at 100% on the Mac you can see the maximum clock speed gradually reduce. This is because the Mac laptops do not have “gaming laptop” cooling which allows for high sustained Turbo Boost speeds.
So two cores at 3.3ghz vs four cores at say 2.5ghz, that’s perhaps why build times are the same (in addition to the OS differences).
Definitely try Swarm since you have two machines, it will help.