I've been having this issue for about 2 months (since getting the phone)... FriendCaster AND the stock Facebook app always have loading issues when I'm on WiFi. The minute I switch to 4G, things run pretty smooth (except pictures -- but I believe this is a known FB mobile bug). I also use a few other apps like gReader (an unofficial google reader app) and sometimes it has tons of problems loading as well while on WiFi.
I've used my mother iPhone and downloaded some similar apps that I have, and her phone runs perfectly fine while connected to Wifi. It's so hard for me to narrow down the problem, because it could be the apps for Android, WiFi, or maybe even the phone. I'm not sure. I'm on ICS .215 leak and it has been doing this since Gingerbread and even throughout .211 official ICS.
Is there some sort of app that could perform like a network app (besides speedtest.net app) that can analyze the connection for potential issues? I even get decent download/upload speeds... I'm just so confused as to why I have problems on Wifi for some reason whereas my mother doesn't. What do you guys think?