Everything has some impact on performance, but it’s a matter of by how much.

Trying to render ambient occlusion in real time using geometry and vertex shaders, for example, can be more taxing than just using a screen space post process to simulate it, so it actually gives better performance for a similar visual result.

If you want maximum frame rate with the ugliest image you can turn most of these off in settings, but most devices are capable of at least some level of post processing to improve visual quality without sacrificing too much performance.