First question to ask yourself during data warehousing (talking from my own experience here)...
How strong is your server? Then, look at your disk speeds and set-up of your disk array.
remember a fully populated array works faster than a half full array. Also separate your dimension loads and fact loads.
I personally had an increase of around 60% odd but simply playing with these variables
Looking at loading stats for me did not help, cause we all know...every server has its own demons