Sound delay - even with airplay 2

When I stream music with airplay from Spotify on my Iphone to the HomePod, there is a 1 sec delay between hitting any button (start, stop, change volume etc) and the reponse on the HomePod. This happens with my Ipad Pro as well. I have IOS 11.4 installed on both devices (11.4.1 on the Ipad), so they should be using airplay 2.

Before buying the HomePod I got the impression, from reading about airplay 2, that there should be practically no latency between the IOS and the speaker. Is the delay I am experiencing normal, or could it be a problem with my Wi-Fi connection or something like that?