I think it is trying to be too large/clever. It is adequately quick when using a fast broadband 65Mb at the moment although there is some delay, however I tried it from a slow broadband 3Mb yesterday and it was too slow to be used.
Almost interesting to see how many (zero) questions there are under the Echo help pages.
Also interesting to see there are NO questions about Kindle Unlimited or PRIME subscriptions. I wonder if this is why all of the SUBSCRIPTIONS threads are still "work in progress". Shame on you Amazon :(