By me, it has helped to disable "resizable bar" in Mainboard Bios. It was enabled by default on my new mainboard/motherboard.
Now Warframe works flowless. no stuttering and laggy.
my hardware GPU:RTX 3090 and AMD CPU Ryzen 7900x MB: Asrock x670e. Newest driver/bios and updates.
on first start with DX12 it needs 5-10 Minutes so compile the shader. in this time its laggy/stuttering.