I think it depends of the version of Nod32, but even thought I think you could compare it with another computer just like yours, but without Nod32, or just do this. Open the Task Manager go to process look for something like egui.exe, ekrn.exe, nod32kui.exe or nod32krn.exe. Then end all of them and try using dolphin. You should have better performance, just look the fps in a specific game before and after you have done that. Also if you want i have a tool that you could use to free ram. but try what i told you first.