If this slow down is only through the PS then the blame likely is Sonys. If I had to guess, I'd say you issue isnt your issue at all, and it's the ISP. If you are using a coax cable modem, you might try backing off the RJ6 connector a thread or two, giving the cable a twist back and forth a bit, then retightening the connector at all of the ends you can reach, then power cycle all of your network equipment (modem, switches, routers, etc.) Test your connection at several different times during the day using several different methods, I am willing to bet you will see different results throughout the day especially around peak usage times 4-8pm on weekdays and starting around noon on weekends.
Not to mention any caps they may or may not be artificially creating because of expansion, or just because. and the depending on saturation, you may be bottle necked from the headends CMTS out to the ISP's network. Network bandwidth has a top limit going from your house to the headend. While you may be paying for 100Mbps, its not guaranteed you will get that. There could be a number of factors outside of your control.
