Why does BioShock 4 stutter in underwater areas on Onda H610E-B?

I felt total despair exploring the deep sea city; every time bubble particles overlapped, the game would hitch, killing my immersion. I tried forcing high-performance mode in the drivers, but while FPS rose slightly, the micro-stutters actually became more frequent. I then used the GamePP Resource Scheduler to elevate the game process priority from Normal to Real-time. After this, the frame time converged to 11-14ms via GamePP Frame Time Analyzer, while CPU-Z showed 3.2-3.6GHz and HWMonitor recorded 68-74℃.