There is no general problem with slow downloads on our service right now, nor recently. A download is only as fast as the slowest link in the chain, and our downloads are stoired and served by Amazon S3, which is about as high-performance a service as one can get anywhere.
Is anyone else using your connection, maybe making a large download of their own or streaming a video while you were testing your download? If you're on a cable internet connection, those often put each subscriber on a LAN shared with their neighbors, so one or some combination of your neighbors could be hogging the available bandwidth. Also, there may be general network congestion or other routing troubles between your ISP and our datacenter at that moment temporarily.
If you're still having problems, try using your Seller Admin > "Send free download link" to send a test link to someone in a different location with a different Internet provider. If they don't have a problem, then it's probably a temporary issue with your ISP or the route between your ISP and our datacenter.