Weird delay in fermentation

My last batch that I did showed some odd fermentation characteristics I have not seen before. I brewed it on 14 August, pitched yeast at 74F. The next morning the temp was 66F and there was a noticeable krausen, ~1.5 inches. The 16th the krausen has lessened considerably and temp was still 66F. I (mistakenly) assumed the major fermentation had taken place since the krausen had died down.
I did not check again until the 20th. By that time, the temp was still 66F, but there was residue for what appeared to be rather explosive fermentation, almost to the airlock. The OG was 1.075, with about 1/3 fermentables coming from honey and brown sugar.

Anyone have any similar experience to this? My previous brews have gotten this explosive in high fermentation, but I never noticed an initial period that died down before things really took off.

You had a lot of simple sugars, so what might have happened was the yeast did the easy stuff and then took a while to shift over to the complex sugars.

That's exactly what happens. The yeast tackles the easy sugars first, then will take on the less desirable ones after that. I don't know the exact order of sugar preference, but I bet if you look on this forum under the 'Brew Science' section, you will find what you are after.