Weird flight performance on Rocky Canyon?

How come “Soviet” jet-planes have excellent performance on Rocky Canyon but Western jet-planes Don’t?
It’s not even something I’ve made up. It’s easy to test this.
I’d be happy to be proven wrong. There’s just no performance on this wonky map. I hope it’s an honest mistake, but it’s not just one country that’s affected.
The performance gap is not at all the same on any other map. The scale of trees compared to buildings and ground textures and sense of speed is totally off.
Any input on this topic is welcome. Cheers!

All soviets ? All western ?

My guess would be the Yak 3 to perform very dably, and the P-47 to perform well …

Jets is my main focus here, but yeah, there are huge discrepancies in other types too.
and Also specifically on the Rocky Canyons map.

What I mean is that some planes perform better at low altitude, and others at high altitude, and Rocky Cannon is very high, sometimes you are over the trees, and you are at 4000m.

Yes ofc, but this is not about altitude. At same lvl and on said map. IE. Same altitude as well.
it’s not the same at other maps. It’s the map that’s weird. Not planes nor efficiency altitude differences.

It is about altitude, the air density due to those altitudes and general aerodynamics of the plane. The same things you’ve said about Rocky can be used in regards to the Afghanistan Map… that is also very high in altitude.

It’s not altitudes man. It’s that map. And only that map. Same altitudes on other maps doesn’t deteriorate my “western jets” nearly as bad. but on 20kft on Rocky Canyon my jets barely fly. Alas the Soviets have not the same issues, I’m avoiding this map from now on. Trees larger than the houses and other buildings and terrain passing by at ground level as if I was flying 80kts in my Cessna 150M or PA-28. It’s just off. weirdly so.