I did not compare it with libgdx but there is a huge drop in mobile devices compared to Unity. In PC, I can say it runs smoothly, in WebGL it is so bad, in Android it drops under 60. if you use lights and shadows (in 2D) the situation is worse even.
My game is a simple tower defense, with vsync set to off, the result for PC is 650 fps and for android is around 50 fps.
The test was for version 2.1.3 that I made and looking forward for version 3 to test it again.