Rendering speed regression in ES2 shaders

[Scene3D][PhongAlphaMaterial]

I made demonstrative example based on my code from QTBUG-54515 (attached).
There are increasing number of entities with PhongAlphaMaterial (every second one more entity is added) and rotating camera.

I found that commit https://codereview.qt-project.org/#/c/182076/ that fixed QTBUG-54994 and allowed to run qt3d apps on android 4.2.2 (QTBUG-55834) and included in qt 5.9.0 and qt 5.8.1 for some strange reason had leaded to rendering speed regression (see video attached).

I also attached compiled apk files.
phongtest_qt5.8.apk (without uroll loops commit) and phongtest_qt5.9.apk (with it).