Looks like the issue is because of the power plan throttling wifi on battery! 1.Add wireless adapter settings to power settings 2.Change power saving mode for wirelss adapter to "max. performance". this fixed the issues on my new 9360 Tutorial on how to add wireless adapter settings is available on eightforums - google "power-options-add-remove-wireless-adapter-settings"
ProblemAfter receiving my brand new XPS 13 I noticed the internet browsing was very slow at times over my Wifi connection. Expecially with web pages that pull in a lot of contact using ajex calls after the initial page load.There was nothing wrong with the Wifi signal or the internet connection itself since other devices showed a good internet speed. Also, downloading files over Wifi was good.FixAfter installing all the latest drivers I finally fixed the issue by disabling the QOS packet sheduler option on the Wireless network adapter. Finally the browsing experience returned back to normal.QuestionWhile this fix works for me I wonder if this is the recommended fix or if there are any other better solutions. 
Very slow internet browsing on brand new XPS 13 9360 over Wifi.