I am not sure, but I think especially Eevee has problems with larger procedural textures.
There probably is a point where Image Textures are more perfomant then Procedural ones, but that depends on the size of the Image Texture and of the Node Tree…So, probably no general black and white answer as to which is better… Do some tests with this specific case to see if there is a big difference and which is better, although you’d probably need to differentiate between speed and memory…
But these are all just guesses from me.
