Ok I have mentioned this for a couple months, as my windows phone rocks and I LOVE Mango, but when I am connect to wifi my phone will not run well. Well I have this posted on the Microsoft forums and somebody mentioned to check the ip settings on the router. I went to my attached devices and watched when my windows phone attached to the router, WHOA. I saw the same mac address and THREE, yes three, ip addresses. This is a bug in windows phone as my wife and I have an ipad, playbook, ps3, android phone and I have had blackberries on it work fine with 1 ip address to 1 mac address. SO, I put in an mac address reservation to 1 static ip address, rebooted router and bam my windows phone is usable. I have weak cell signal and when we connect to the wifi, smart phones and apps run great, now my windows phone is rocking. So posting this for all, on all types of windows phone (seen this xda forums and happens to other people) if you have issues with slowness, check your router attached devices to see if your phone grabs more than 1 ip address. Enjoy.