I agree with Chris' assessment. eglSwapBuffers blocking for so long (over 32ms, i.e. 2 frames at 60Hz) is causing Qt's main loop to block, compounding the stutter.
I agree with Chris' assessment. eglSwapBuffers blocking for so long (over 32ms, i.e. 2 frames at 60Hz) is causing Qt's main loop to block, compounding the stutter.