wp8 memory problem


I did some investigation about memory usage on wp8
In the HelloCpp demo in cocos2d-x2.2.1,
on wp8 emulator, it will add a 2048 * 1536 size “helloworld.png” as a sprite,
I use Windows::phone::System::Memory::MemoryManager::ProcessCommittedBytes to get current memory used by my game, devided it by 1024 * 1024 to get it in MB

before CCSprite::create ProcessCommittedBytes is 9.847656
after addChild add it to scene ProcessCommittedBytes is 21.875000
after it is displayed on screen, ProcessCommittedBytes is between 35-37

so it takes two times as much memory, is it ok?