The game runs pretty decent on PC. However, it looks very bad on my iPhone and android phone when running through Unity remote.

I have tried different combination of quality setting but it seems nothing changed.

Anyone please explain why the quality and running speed is so different between these platforms even through on a fast setting.

Unity Remote is just for testing and is much slower than a build. It’s just for testing if input works. You can use the input from Unity Remote and keep your eye on the editor where it should be smooth.

You also have a decent amount of draw calls.

Through unity remote it will be like that only. Try taking a build in a device.