Advice/Hep Building Supertux so it's faster on SailfishOS

[enigma9o7]

I built supertux from github source using ENABLE_OPENGLES2 cmake option. It runs fine, but is slow, like running emulator on a too slow of a pc, sometimes its ok, but sometimes everything slows down, sometimes it starts and stops....

I would like any advice as to how to make it run fast. When I was on Android the play store version worked fine. My old 32-bit pentium 4 can run without slowdown.

Some info: I am building this directly on the device. I do not have much experience building from source, but can follow directions. Supertux worked this way, just had to install the right packages first. Besides the slowdown, there is only one issue - it is rotated 90 degrees, but I have a workaround for that, but if there's a way to build it so I don't need to rotate afterwards with another application, that would be good too.

The device itself is F(x)tec Pro¹ keyboard smartphone.
Linux 4.4.153-perf+ GNU/Linux Sailfish 3.2.1.20
Building on device for armv7h
Plenty of CPU I think...