In short, I’m not sure that there’s a lot you can do with getting it to higher settings. The easiest way to tell that it isn’t the device would be to use a higher spec device on the same network, which isn’t all that practical for everyone and would leave the game on someone else’s phone for single device owners
I’m not sure that there’s much you can do about the J with 1.5GB RAM, when I’ve seen War Dragons take up 2 GB and sometimes 4 GB, when it’s being bad. PG isn’t entirely free from fault due to things like issues with memory leaks and other issues with Android (also just too much different hardware). Processing power and GPU might also play a factor as well.
For comparing with other games, you’d want to compare with ones with full 3D rendering, which is why some of the lower spec phones can suffer.
It doesn’t seem like PG distributes its network either, so physical distance from the servers also matters.
You can try poking support, but my guess is that it’d be the usual hard restart, reinstall, device restart stuff, which can help every once in a while but often not