I almost feel sorry for Flash. Kicked to the curb by Chrome and then Firefox, it won't be long before Microsoft turns the screws. Not that you have to wait for Redmond to get its act together -- you can turn it off right now and get a nice performance boost.
Noticing that Edge wasn't running at its best, gHacks' Martin Brinkmann decided to investigate. After playing about with the browser's experimental flags (via "about:flags"), it turned out that something a lot simpler was at fault: Flash.
For whatever reason, just having Flash enabled was enough to make Edge less responsive for Brinkmann. Fortunately, it's easy to put the plugin out of its misery:
Click on the menu icon (three dots) in the upper right corner of the Microsoft Edge interface. Select Settings from the menu that opens. Scroll down until you see the advanced settings button. Click on it. You find the "Use Adobe Flash Player" toggle near the top. Set it to off.
And that's it. Chances are you won't notice the difference, though if you're a heavy Flash user... well, you have a lot more on your plate to worry about!
Speed up Edge by disabling Flash [gHacks]