I hope not, I'm pretty sure that some arrows wouldn't affect so hard the performance of an Android phone. And if they do, well, it's time to bring some serious Android developers to the team. But I still hope it's not the case.
Anyway, they can be seen in 2D mode so if they affect the performance so hard, it shouldn't be displayed in 2D either. One more reason to think that's not the reason.
Regarding the screen size, they are not available on 3.5 but not on 4.8 either. So .... 4.8 inch screen is big screen after my opinion
And even on 3.5 the arrows in 2D mode are displayed just fine.