FPS surges on Galaxy S7 (Gear VR)

We have stable fps ~59-60 on test scene. But sometimes fps drop to 29-30 for a few milliseconds. This issue only on Galaxy S7. Galaxy S6 have stable 59-60 with jumps to 55 fps.
What could be the problem? Tap on touch panel to open debug menu.

Unity 5.6.0f3 (64-bit)
Build Url - https://www.dropbox.com/s/xz3tig2trl50m6g/1.apk?dl=0
Project Url -...

FPS surges on Galaxy S7 (Gear VR)