Can anyone recommend some shaders for environment surfaces for mobile?

I have a mobile build of my game, and currently use the built in mobile diffuse/bumped diffuse/bumped specular shaders for the track surfaces for my racing game.

And as we all know, the Standard shader kills performance on mobile devices, so I avoid these.

Are there any 3rd party shaders that are performant on mobile you can recommend that look good?

Any asset store recommendations?

Thanks