Lightroom 4 runs slow

i have purchased lr 4. must prefer lr 3 more. find runs extremly slow , i'm not happy took recovery , brightness sliders away. noticed took preset of tone medium away on left hand side. have done updates but, didn't seem much. exporting images editing images slow. i'm not sure defringe , moire brush used either. suggestions apprecaited. thanks!

there free tutorials on new features of lightroom can access @ link below. worth viewing time.