I have PIA with a Telus 25 and Eastlink 20 connection. In either case, with PIA running (I have a tomato router on each connection) I have never gotten more than about 3mbps while downloading, no matter if I'm using a US, Canadian or European setup. Eastlink sucks at any time (that 20 mbps connection usually runs around 5), but Telus can rock the full bandwidth without the VPN running.
Running the VPN on the router, or on the PC doing the downloading?
My experience to date with VPN on routers, even FAST routers, is that they choke the connection trying to keep up with the crypto. Running it on a fast enough PC gives me wire speed (30-45mbits/sec download). Running on a router chokes things down to 10-20mbit/sec, as does running it on a low-power Atom-based netbook.