Few days ago installed STEAM platform on my computer (Windows 10) , just wanted a play a game. The GUI was very very slowly. It took me few minutes just to create and enable an account. Then to browse and install the applications store was impossible. Thens searching on the net I've found different hints/solutions. The want that worked for me was to change the settings for Internet Options. Just go to ControlPanel->Network and Ineternet->Inernet Optins, and a popup will appear. In this new popup select Connections tab and then LAN Settings. After that uncheck the option Automatically detect settings, like in the picture below. After doing this everything was fast, tens of times faster.