Must say...

Drew1903   Metrics come and metrics go.  Chrome and Edge (Classic) have battled back and forth in the speed wars, each claiming a small edge (no pun) over the other.  Different tests (and normalization methods applied to the tests) yield different results, and both Google and Microsoft claim superiority.  It is somewhat horse hockey, because the measured speed advantages that MS and Google are touting back and forth are generally in the 3-5% range, once normalized, and in the past few years, Edge seems to have the performance edge (this time it is a pun).

And yet user experience is that Chrome is much faster in comparison to either Edge.  Reviews in the trade press almost always comment on how fast Chrome is in comparison to Edge.  Those reviews probably should read "how fast Chrome appears to be in comparison" because the metrics do not support the experience.

I've experienced the same thing you have with respect to Edge Chromium: "Wow, is this fast!"

So I started to think about the question of why I think that when I have no metrics.  That led me to think about why Chrome reviewers (and users) think that about Chrome, too.

From what I've read about the issue in the last few days, the difference between Edge and Chrome in percieved performance is the result of the way in which Chromium handles processes.  As Chromium  opens a website, the browser https://blog.chromium.org/2008/09/multi-process-architecture.html to open various elements of the page, and pages "snap" open since different elements of the page are being processed simultaneously rather than sequentially.  Edge, on the other hand, bundles processes, using many fewer processes to open a website, combining similar elements into single processes.

In that single respect (opening web pages) Chromium-based browers (Chromium/Linux, Chrome, Vivaldi and Edge Chromium) are going to appear to be (and probably are, although I haven't seen the metrics testing just that element of browser performance) much faster than Edge (Classic).

But opening multiple processes comes at a price -- Chromium-based browsers are resource hogs. 

Run Edge (Classic) and Edge Chromium hard (that is, open lots and lots of websites, in tandem doing the same things, and then check Task Manager for the number of processes that are open.  I think that you'll find, as I consistently do when I look at Task Manager in those circumstances.  And keep an eye on memory use between the two browsers.  I seldom see Edge (Classic) use more than 1gb of memory, and I often see Edge Chromium using 2-3gb during those comparisons.

All the open processes and all that memory use is the reason that Chrome has a reputation as a resource hog, and Edge Chromium is no different in this respect (as we can see for ourselves on Task Manager).  

So the speed is there in Edge Chromium, but it comes at a price.  Where the rubber hits the road in this respect is when Edge Chromium is running on low-resource computers and when Edge Chromium is running on a laptop. 

On low-resource computers (that is, low-end processors and 4gb RAM) heavy Chromium use bogs things down, sooner or later, as multiple processes consume processor resources and high memory use burdens the computers other running processes.

On laptops, Edge Chromium eats up battery resources noticably faster than Edge (Classic).  Microsoft used to make much of the Chromium-based disadvantage in the battle between Edge (Classic) and Chrome, claiming that Edge got 35% +/- better battery time than Chrome.  Independent testing has confirmed that Chrome drains batteries much quicker than Edge (Classic).

I've noticed lower battery life on both laptops that I'm using to test Edge Chromium.  One is a mid-level business laptop (Dell Latitude 7280, i5 8gb) that normally gets 10-12 hours of battery life in ordinary use.  The other is a low-end laptop (Dell 3815, AMD 9-9420e, 4gb) that normally gets 4-5 hours. 

I use the laptops in predictable ways.  I use the 7280 almost every night, browsing here and there for an hour or so, nothing demanding.  I use the 3185 on Tuesday and Thursday at the railroad museum where I volunteer, first checking around the museum's networks to see that all is well (or not), and then active/sleep on and off during the day as the need to check something online arises.

There is a noticeable difference between the battery life I obtained when running Edge (Classic) and the battery life I've obtained during the last couple of weeks, running Edge Chromium.  Instead of 10-12 on the 7280, I'm getting closer to 8-10, having to recharge more often than I used to.  On the 3185, I have to be very judicious about use in order to nurse the computer through the working day, where I didn't have to think about it at all before Edge Chromium.

So its a trade off, Drew.  Performance comes at a price.  Nothing new.