I'm going to go out on a limb and guess that the fastest way to get golden eggs is to camp barb fishing, regardless of whether you already have the eggs. Prawn balls are so fast there, it seems to me that you'll get the eggs much faster than fishing the worse spots. (Plus I find it much more engaging than, for example, rocktail fishing where catch rates are so low.) I know I got the majority of my eggs for my first time through there. I recommend saving up the mystery eggs until you have all three leaping fish so you don't waste them and get one of the leaping fish with a mystery egg.