can anyone explain to me what the differences in speeds are? how much do they affect how fast your village grows?

crazychick, normal speed ages your peeps a year for each two hours, and they do two years of work in that time. Half speed ages them a year every 4 hours, and you get 1 year of work each two hours.

After reading that it sounds kind of confusing, so let me just say that on half speed they'll get half the work done as on normal speed.