Battery and graphic performance

Am curious on what kind of specs you have?

For me personally Chrome / EdgeChromium doesn't have working hw accelerated video (Intel HD 3000) and I tend to use EdgeHTML for streaming because it is much more fluid.
Haven't tested the browser on a Surface Pro 5 yet but I mainly stick to EdgeHTML for surfing.

"In one test that is a multi-layer map, EdgeHTML renders all the layers instantly at once, and with EdgeChromium/Chrome the layers paint in, with transparent images in upper layers requiring an additional redraw each layer beneath it. Then when scrolling the map, EdgeHTML is instant and the map looks like a single image, where in EdgeChromium/Chrome the layers redraw with each shift."

"As a colleague referenced, Chromium uses a document/display model, where IE9-EdgeHTML use a compile/execute model, and the feel is very different, with Chromium feeling more like IE8 than the last 10 years of IE. (Sadly)"

From what I understand EdgeHTML/Spartan renders pages in a much more efficient manner whilst also having a lighter footprint and better optimised hardware acceleration.
This is really noticable on older hardware.

Sincerely hope that the Edge dev team manages to make improvements to the hardware acceleration and rendering of sites/pdf docs.