Here’s how it works:

Update to Microsoft Edge Beta 125 (or later).
Navigate to Settings > System and performance.
Under “Manage your performance,” enable the toggle for resource controls.
By default, resource controls only activate during PC games. But you can choose to apply the RAM limit all the time by selecting “Always.”

Keep in mind: Setting a lower RAM limit might lead to increased page reloads and discarded tabs as Edge tries to stay within the limit.

To monitor your RAM usage, you can use the Browser Essentials sidebar. This sidebar also lets you toggle efficiency mode and see memory usage related to sleeping tabs.

For those users who are concerned about exceeding the limit momentarily, Microsoft assures that Edge will do its best to stay below the set value. There might be instances of temporary spikes, though.

If you’re a Microsoft Edge user, especially one who games on their PC, this new resource control feature is definitely worth checking out. You can try it out in the Beta version.

https://mspoweruser.com/microsoft-introduces-resource-controls-to-set-how-much-ram-edge-can-use/