FPS is very low on certain embedded devices

With Scene3D, even a very simple 3D scene is rendering on very low fps (10~20fps) on lower spec devices such as Renesas R-Car D3 or E3.

Examples:
1. This runs at ~20fps (@1280x720) on D3 even though original example on Qt3DExtras::Quick::Qt3DQuickWindow runs at 60 fps even on D3.
https://git.qt.io/notohge/scene3dexamples

2. This runs at ~30fps on D3.
https://git.qt.io/unryu/ArHudPrototype