This might happens in certain websites and there are many reason behind it such as scripting loop like an script is loading incorrectly or they might be several programs running at the same time and consume a lot of resources and affecting the performance of the Microsoft Edge.
When you encourage such a issue, first ask the user about the website or webpage causing this behavior and try to test it out in your system with Microsoft Edge to see whether this is an issue with the website or the system. In case, it reproduce in other systems, you need to inform the website owner about this issue.
In case it was specific to one system, check and make sure that Microsoft Edge is fully update. Verify if the issue is reproducible without any extensions and InPrivate Browsing mode and also check resources such as CPU and GPU.
Also check edge://settings/system and verify whether this is reproducible when Hardware accelerator is off and if yes, then you will need to check your GPU and update it.