Mine normally takes 40 mins to download, but only 20mins yesterday. I've got full fibre broadband but that hasn't made it any quicker (until yesterday). I suspect that a lot is down to the HERE server bandwidth - the more there are downloading the slower it runs.
Incidentally, I bought a Sandisk 64meg USB stick and didn't need to format it - just plug in and go. I did try a 32 meg stick first, as LR recommend, but it didn't have enough space. Presumably the formatting takes up a little bit of the memory and that means there's not enough for the download.