DSL performance is very sensitive to the length and quality of the copper pair between your home and the Central Office.
Having said that, the first thing to check is the router log and see what rate it has been able to negotiate on the link, and what the losses are in each direction. If the negotiated rate is well below 3mb/768kb, either Verizon hasn't properly provisioned your line, or the copper pair just isn't good enough.
If the router says it has a good link (>3mbps/>768kbs), then the problem may be with your computer, or network congestion, or any of many possibilities. So check the modem/router log first. Each time it establishes a DSL connection with the Central Office it makes a log entry with the connection speeds and losses.