I'm having some strange behavior with my Win 8.1 devices on my network.
First, here's the results from my Macbook Pro and Mavericks on WiFi.
Then here's my Lumia 920 Windows Phone 8 on WiFi
Here's my desktop PC wired straight into the router
And here's my Surface Pro through WiFi
I also tried my desktop PC over WiFi but was getting the same slow speed so I quit it. I never really checked before I upgraded to 8.1. I only checked because my network was slow last night but it turned out to be my Surface downloading all my apps.