Using Cubase for midi only(No ASIO)

Greetings all, new here.

I use external hardware in Cubase and noticed that the midi still functions without an Audio Driver selected, is there any hidden gotchas to doing this or is it stable?

if so where is the clock source?

I do noticed that Cubase does not seem to rely on the audio buffer settings for midi like other DAWs where the higher the buffer the bigger the delay with midi despite not using soft synths.

Any thoughts on this?