Today PC World wrote a interesting article titled Slow broadband? Blame the neighbour's Wi-Fi and in the same day the inquirer wrote WiFi speeds are much slower than cable.
These are two points that I stress when people talk about issues with buffering/stuttering. In many cases is badly configured wireless getting interference from neighbours or even your home HiFI/Microwave/TV/Electric Extensions/Mobile Phones.
Then theirs the fact that WiFi is awful for streaming tv! Ask any PC gamer and they will tell you not to use WiFi for gaming because of lag, this is the same with streaming tv.
Cable's are better then wireless. (with mobiles we have no option )