Just started happening to me today, started a match of R6S and experienced really low FPS (which never happens) and tried to find out why and saw that AMD's Radeon Relive makes the GPU usage be 75% at idle, and at stress it's laggy and unbearable. Radeon version is 18.3.1 (latest)
Go to this thread who has identical problem with GPU opened yesterday or today: Core clock not dropping back to 300, memory does. Since 18.3.1
It's been a couple of years since this post was published, but I still experienced this problem 'till this day. Today I started trying my own solutions, starting by disabling Desktop Recording, which didn't help sadly. But, I did find a solution (this has worked for me for a couple of hours now, so I guess it does work). Whenever I don't have any stress on my GPU the Radeon Relive will indeed use 75% of my GPU, but whenever I load a game this percentage goes down. What you need to do, is open Task Manager, and right-click on the Radeon Settings: Host Service. Then press 'Go to details'. Now the AMDRSServ.exe will be highlighted, right-click it and then go to 'Set Priority'. Whenever the drop-down menu comes up, select 'Normal'. And whenever you open up your game, set the priority of your game to 'High'. Now the game will take over the priority of the GPU usage, and the percentage of Radeon Relive will adapt to the amount of usage of your game.
I hope it works for you guys, I am extremely happy it does for me!