Too Slow Rising Challah
What causes a bread to rise too slowly?
I have been baking Challah regularly, using a sweet Challah recipe adapted from Jeff Nathan's Honey Challah recipe. The original recipe suggests using active dry yeast, but I substituted instant yeast (cheaper and easier). I also noticed that the original recipe uses about 2.25 cups of water (1 cup to proof the active dry yeast, and then 1.25 into the recipe). When doing this, I reduced the water to a total of 1.25 cups of water (.5 to make a yeast slury along with .5 cup of flour and the yeast and then .75 cup into the recipe). The recipe also calls for 1/2 cup of sugar, 1/2 cup honey, 1/2 tsp. of vanilla, 1/3 cup of oil, and 6.5 total cups of flour, as well as two eggs.
When I make this, the first rise can take up to 3 or 4 hours to double in size. I've tried osmotolerant yeast, regular yeast, etc., but nothing seems to get me close to the 1.5 or 2 hours of rising time to double the loaf. The result is generally excellent (although sometimes the challah dense and doughy), but the rise times are simply too long. The taste is very good.
I tried making another recipe, and the challah rose much faster.
Any ideas? Something is weird about this recipe.