Make sure your games are on a SSD, this isn’t optional anymore; modern games often rely on loading assets as they are needed and if they fail to do that it could appear to stutter, among other issues. This is particularly important for UE games.
Additionally that smearing effect you mentioned could be FSR loading low resolution textures. Try tweaking your settings related to it.
Confirm, that your AMD drivers are up to date. Also If your ram supports XMP or a equivalent feature enable it to benefit from your ram. This is often overlooked.
Enable “Above 4G Decoding”. Consult your motherboard manual for details on how to do that.
Additionally if your game offers a choice between directX or Vulkan.
Choose Vulkan, if you experience problems try the DirectX options.