Slow performance on better GPU

I have 3 android devices:

The tablet (I firstly interested in it):
MediaTek MT8735, 4x ARM Cortex-A53 @ 1.44 GHz, RAM 2Gb, GPU Mali-T720 (1 core), OpenGL ES 3.1, 1280x800, Android 8.1

Xiaomi Redmi 1S:
Qualcomm Snapdragon 400 MSM8928, RAM 1Gb, GPU Adreno 305, OpenGL ES 3.0, 1280x720, Android 7.1.2

The PAD (noname tablet):
Qualcomm Snapdragon 400/410, 4x ARM Cortex-A53 @ 1.21 GHz, RAM 2Gb, GPU Adreno 306 @ 400 MHz, OpenGL ES 3.0, 1280x800, Android 5.1.1

I ran several 3d benchmarks. See pictures attached.

Except one test (Depth of Field in GeekBench) Mali-T720 (tablet) showed better results (in fact twice better on average) than Adreno 305 (Xiaomi Redmi 1S).
(also benchmark of tablet CPU is twice better than Redmi 1S).

Made Qt test app (attached) based on scene3d example with 3 scenes:
Scene #1 - default objects and materials (from scene3d): sphere rotated around torus, both with PhongMaterial component.
Scene #2 - same sphere rotated around torus, but now both with TextureMaterial component (it seems less GPUresource-intensive to me).
Scene #3 - sceneloader that load helicopter model very close up to camera.

The measured fps values (in two modes: with multisampling enabled and without it) are summarized in a table

I'm working with Qt 5.9.5. Tested app built with Qt 5.12.0 for arm64-v8a for the tablet - same results.

p.s. Also I have Xiaomi Mi2 (Qualcomm APQ8064 Snapdragon S4 Pro, RAM 2Gb, GPU Adreno 320, OpenGL ES 3.0, 1280x720, Android 4.4.4) and it renders 60 fps all scenes with multisampling. Android is quite old, so I could only run AnTuTu benchamark on it: 3d marooned - 2.40 fps, 3d garden - 1.19 fps.