A lighter sky
Forty warbirds, the flak batteries, the towns and the forests, all over one map, is a lot to ask of a phone. It's now a lot less work. Same planes, same sky, and a steadier frame when the fight gets crowded.
Same sky, less work
Every plane in the sky is really four planes. There's a fully detailed one for when it's close enough to count the rivets, two lighter builds for the middle distance, and the classic blocky silhouette for a speck on the horizon. You only ever see one of them at a time. Until now your device kept all four flying anyway, every one banking, climbing and spinning its props in step with the one on screen. Now only the plane you can see does the flying, and the others wait until it comes into their range. The same goes for every flak gun, tank, truck and warship on the map.
The forests and towns below got a smaller tidy-up of their own, so they stop getting in the airframes' way when your device works out what to paint next.
What you'll feel
On a fast desktop the game already ran at full speed, so you may not notice a thing. On a phone or an older laptop you will. In a busy furball over the ring, a phone-class processor now draws about a third more frames a second than it did. That's the difference between a gunsight that stutters across a crossing target and one that tracks it smoothly through the whole pass.
What you won't see
Nothing looks any different. Planes still trade their detailed build for a lighter one at the same ranges. When a Leviathan closes from a speck on the horizon to a full airframe filling your windscreen, every swap happens right where she's flying, with her paint and her battle damage where they belong at every range.