Dolphin can READ BACKUP discs directly (through File => Boot Disc). Original discs must be dumped first. Furthermore, when booting backup discs directly I didn't notice any performance issue (however, in some games the loading times may be long than when running the ISO file directly)
Avell A70 MOB: Core i7-11800H, GeForce RTX 3060, 16 GB DDR4-3200, Windows 11 (Insider Preview)
ASRock Z97M OC Formula: Pentium G3258, GeForce GT 440, 16 GB DDR3-1600, Windows 10 (22H2)
ASRock Z97M OC Formula: Pentium G3258, GeForce GT 440, 16 GB DDR3-1600, Windows 10 (22H2)