Ignore Z axis in material displacement - is this a good way?

I have a material that is displaced by normal map, but it gives undesirable effect - it lifts up the object slightly on Z axis. I’ve fixed this by ignoring Z axis like this:
[The input is my normal map and the result goes to displacement input]

It worked, but would it be bad for performance? I’m a material noob and I’ve just figured out this workaround in similar fashion to breaking Vectors in blueprints…

… Is there a better way, or is this solution ok?

OK, I’ve figured out a better solution: Multiply by (1,1,0) vector. It works and if I’m not mistaken, it can’t be simpler now…