[Newbie Alert!] First experience with OpenElec on Pi

Hi all!

So this week i got myself a Pi with the intent to run XBMC on my TV in the bedroom. Wifi AP is in the living room. I'm living in an appartment and my two laptop i have in the bedroom also use the same AP without any performance issues.
Installed OpenElec and all is working. Installed the Add-Ons i wanted and found out that the system is really slow accessing external sources like xbmchub.com where i get most of my add-ons from.

So my question is this: Is it the Pi that is slow or is it the Wifi? Browsing the menus is snappy enough. It's the loading of the add-ons and using them that is slow.

The Pi is completely standard, no overclocking that i know of.
I get the power for the Pi from the USB on the TV.
I use one of those very small Wifi USB plugs (http://ecx.images-amazon.com/images/I/31O3dfinGIL.jpg).
SD card is a 16Gb Class 10 SanDisk.

I am planning to try the Pi in the living room closer to the Wifi or even using a wired connection (not possible in the bedroom) to see if that makes a difference.

Any ideas?

Thanks,

Ton.