Speeding up Map downloads ???

The download depends mostly on your internet provider, speed, and Garmin's servers. Regardless of where the map is to be installed (nuvi or SD card), the download is first stored on your computer's hard drive. The map transfer to the nuvi or SD card is where the throttling occurs. The old USB 1.1 speed used by the likes of the nuvi 750 is slow, while the newer nuvis are speedier. Transfers to a SD card are probably going to be faster, depending on the speed of the card reader, whether built into a computer or connected to a USB port on the computer, and if a USB port, is it a USB 2 or 3, etc?

What CraigW said is correct. The Garmin Express or Map Updater process will in most cases be faster with cloning, but the only the portion of the procedure where the downloaded files are copied to the clone (SD card) is faster. And if you do as I do, you still end up manually copying the updated map files (as many as possible) from the clone back to the real device. On old devices like my 755T, that copy process is painfully slow. So for me, cloning actually adds additional time. On my 755T, it took over an hour to manually copy the 2017.20 map from the clone SD back to internal storage.

Now, if you plan to leave the map and as many other files as possible on the SD card and operate the nuvi with these files on SD instead of internal storage, cloning probably will save you some time on map updates.