Here's an interesting (to me, anyway) bit of trivia about the use of the Hotspot Shield VPN, which I just experienced. Typically when one uses a VPN for security purposes over a public wifi network, the download speed usually drops -- for several reasons. This is expected, and is just part of the price one pays for additional security and to prevent hackers from 'sniffing' your computer or tablet.
I'm presently on a secure wifi network in our condo and don't need to use a VPN. But from time to time I like to check out various VPNs to see how they perform. Using Cox Cable I just now got a download speed of 28 Mbps, which is perfectly usable for normal computer use. I then opened the Hotspot Shield VPN, selected a server in the U.S., and after a few moments it got connected. I don't know where the server was located in the U.S., just that it was connected.
I did the download test again and got 42 Mbps -- a significant improvement and a nice surprise. I did this same test earlier this morning and got similar, favorable, results. Hotspot Shield VPN is available for a Mac, PC, iOS and Android. They offer both a free and paid version.
So, if you occasionally use public wifi, I suggest that you use a VPN, whether it be this one or another.