Mine is over UK rural broadband, 'superfast' FTTC, which when you're this far from the cabinet means on a good day 9-10Mb, and Alexa normally responds quickly. I just asked her the time and she answered immediately, maybe a half second delay, but that just seems polite ;-)
It's not really the delay that is disconcerting, it's the hearing what I've just said repeated, usually just as I've started another sentence. Hey ho, I'll just have to restrict my conversations to "dinner's ready" and walk upstairs if I need to say more!