There’s no 3D model parsing in JUCE, so it would be up to you to either roll up a model loader or use an external library if you wanted that. You could try your hand at integrating the slightly daunting Autodesk FBX SDK into a JUCE project.
There are also sprite sheet like knob tutorials on the forum: see Skinning the Slider / Replacing knob and slider track with PNGs .
Well, I don’t think performance is the main concern here: usability and maintainability are. Managing input events with 3D models is a rather large task that it’s just less headache prone to use what JUCE offers out of the box.