OpenGL performance in JuceDemo

Something suprising that I have noticed on my retina macbook (on macos):

Launch the JuceDemo, select “Use OpenGL renderer” and switch to the “2D rendering” demo. The animation is super smooth , runs smoothly at 60 fps on my retina screen.

Switch to the ‘OpenGL’ demo, and switch back to ‘2D rendering’ : the animation is now much slower, the actual fps reported by juce is ~20fps.

I wonder if this is because of an issue in juce opengl code, or is just the kind of things one has to expect when using OpenGL (crappy drivers, strange bugs, and bizarre issues like this one) ?