Your score is not based on how fast you go, it really depends on how fast your customer pays. Though you do need to go as fast as you can, you really need to make sure that your customer is paying quickly. You might want to ask them in advance how they will be paying. It is really hard to say what you need to do without watching you check someone out. And 140 is a very difficult score to achieve, unless, of course, you are at a store that is self-unload and not customer-unload. I hope I have been of some assistance.