The fermentation takes a certain amount of time and it's not going to take less time because you're making less of it. The process is yeast eating sugar and producing co2 and ethanol as waste products. I know it seems like it would be faster, but it isn't. Some of my wines take a really long time to ferment even one gallon. Wine making and beer making aren't really good hobbies for inpatient people! Good beer takes about 6 weeks, and that's for "regular" beers. Anything higher alcohol like a big beer or wine takes longer.
Broken Leg Brewery
Giving beer a leg to stand on since 2006