On my desktop fans do kick in when opening websites in Edge, for example now when I was opening this thread with only one tab open and only edge and task manager running CPU usage went up to 50% when it was loading ads but then dropped back to 5%.
When opening Microsoft.com the CPU usage was 29% just the moment before it loaded and when I was opening mspoweruser.com the usage was at 30% at it's peak but then dropped down to 5%.
Not sure what your CPU is, I am running a Core i5 7600, if your CPU is a bit older then that's probably what to expect because I believe they used more CPU power for better performance because I can tell that before the Creators Update Edge was even slower when I was opening Windows Central.