I have a farily beefy PC: RTX 3080, 64GB RAM, and an EVO 970 M.2 SSD (separate from the OS) and the ‘Highest Quality’ megascans give pretty terrible editor performance. If I were to do it over again, for the purpose of learning and completing the course, I would probably choose ‘Lowest Quality’.
Even disabling the fancy UE5 features like Lumen, and virtual shadowmaps, I eventually had to reduce the texture size of all megascan assets to 2048. Only then did the editor performance become okay (It would stutter and dip to 46-48fps).