Your speed test at 3Mbps has not much to do with real download speed.
Speed test servers are dedicated to do just that - speed test. It's like having almost perfect download enviroment.
When you try to download some real file, the speed depends on quality of servers, quality of your connection, time of the day, how many users are accessing that file, etc.
What type of connection do you have, and what is your ISP advertised speed?
Post also a link to some download, and we'll see, if we're getting similar download speeds.