DD-WRT doesn't make the router a beast, it more or less adds more router control options. It does not increase performance. Though it does make the gui for the router better and more user friendly. I suppose that makes it run better(in theory).
it did have improvements though, the additional features, or maybe the firmware itself had something that made them more versatile and even reliable.
for one the added congestion controls did make internet access more fluid, the other is that the firmware itself seems lighter(cpu usage was lower).
