graphicconception: OMG! That is a sign of Global Warming.
The warming will heat the wires and that will increase their resistance. An increase in resistance will reduce the amount of current that will flow for any given potential. Capacitors will take longer to charge up as a result.
Your computer and the Wikipedia servers will contain billions of capacitors.
Click Refresh. If it still takes too long to load, load up a different website. If that loads up fine, Wikipedia is having problems and you should try again later. If the new website takes too long to load up, some idiot is using up your bandwidth and you need to find them and tell them to stop downloading all those torrents.
Reboot and it's likely to be better.
Happens to me as well, not just wikipedia, and I haven't figured out why.