Since installing the Edge beta and restarting it a few time I have observed a problem with a service called sysmain using larger amounts of system recourses. This may be completely unconnected from the Edge Beta and I simply didn't notice it before however I thought I would share just in case anyone else has experienced the same thing. It normally sits at around 30% of the CPU usage on my Surface Book 1 and doesn't subside until I force it to end the process. This spawns another process with high usage which I also kill which then fixes the problem entirely.
Based on what I was able to see on my own system, Sysmain is the first subprocess of the Microsoft Edge Insider Build process tree. It is running everything that isn't specifically part of a single Tab in the Browser.