[Libgdx] Basic code stuttering on HTC Desire 816

I started making my little game for Android (Not so little anymore), using Libgdx. Recently I started testing it on some shit device (Sony Ericson Xperia, really old, slow device) and the game was running pretty well. Then I borrowed android device from my bro, and the game seemed to stutter like crazy.

I created an empty Libgdx project with nothing in it, and ran this basic code.
Even when rendering this basic rotating square, the app seems to stutter. (Running on HTC Desire 816)

Any ideas? I wouldn’t really want to rewrite all the code I have written so far in C++ o-o