30s isn't really typical; the average is in the ballpark of 10s. When I worked at Square we got our average down to 4.2s [1]. Modern Verifone terminals seem pretty quick as well. Long term, "instant" contactless will probably become the norm (though it's taking hold very slowly in the US).

[1] https://squareup.com/townsquare/weve-chipped-away-at-emv-tra...