It runs fine on my Samsung M23 (2.2 GHz) where it defaults to 60fps, but I will double check the framerate.
Before the latest update I optimised a lot of systems, to the point where I can get a web build to work. If you're able to connect a gamepad to your phone you can try the browser demo to see if it's just as slow (it runs just as fast on my phone).
Finally, can you post what phone you're using please? It might be a hardware issue. I can't promise I'll be able to fix it, but at the least I can let others know of potential issues.