[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.
http://www.java-gaming.org/?action=pastebin&id=1135
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