If you need the fastest, build your own. Add a second network card to a pc or use a motherboard with two built in. There are some great atom boards with 2 nics. Install PfSense, monowall, dd-wrt, or your choice of router os. You can be up and running in no time with a very powerful router you can customize as you need. PfSense is especially easy to install and configure.
Connect one of the nics to your modem and the other to a gigabit switch.