... Don't run your disk defragmentor on your laptop when it's not plugged in. My battery went down fast! It seems so obvious in hindsight.
On the bright side, the defragmentor kindly told me after it had drained my battery down to 20% that it was stopping the defragmentor because it was low on juice.
I would have been impressed if it had warned me before hand. Something like "Warning! Your computer is not plugged in. Running a disk defragmentor will suck your batteries dry. Do you want to continue?".
I think it's that sort of friendly polish that gives people a warm fuzzy feeling about a product.