Although the connection to my router is fast, why is the internet so slow?

I've hooked my laptop up to my home's wireless network. Windows reports that the connection speed is 36.0 Mbps, but the internet is very slow (if pages load at all, it can often take 15 minutes). The problem doesn't seem to my my network card, as I have connected to other wireless networks in the past and they all run quickly. The internet is also fast when I plug in directly.

Is there some sort of problem that could be preventing the internet from running fast (even though my connection to the router is fine)?