I have fairly old dishwasher, probably not very energy efficient. It finishes it's job in about 1:30. If I would have a more modern, energy efficient but slower dishwasher, in a four person household I would need more dishes. Now the fallacy is, more dishes (if you have the space to store them away) are far more cheaper on the long run but sticking to your old dishwasher. Take-away: Get a new dish-washer.
Moved into a place that has a Kenwood thats a few years older, maybe 5+ and I hate everything about it; not only does it not clean my dishes as well, it takes ages to do it, and it will beep forever until I switch it off after a cycle finishes.
We intend to replace it with another Bosch as soon as we can, but we just moved so, priorities are elsewhere right now.
Take-away: Get a new dish-washer as soon as possible.