For downloads it's buffers in your ISP's hardware that matter. For uploads it's your router's egress buffer.
e.g. You are syncing gigabytes to Dropbox. A poorly designed router will continue to accept packets far past upstream capacity. Now that's there's 2000 ms of bulk traffic in the router's queue, any real time traffic has to wait a minimum of 2 seconds before getting out.
e.g. You are syncing gigabytes to Dropbox. A poorly designed router will continue to accept packets far past upstream capacity. Now that's there's 2000 ms of bulk traffic in the router's queue, any real time traffic has to wait a minimum of 2 seconds before getting out.