Why do fast machines have to wait longer for credit than slow ones?
If you have a fast machine, the odds are higher than you will be the first person to return results for a given workunit. The odds are also good that the other machines that get assigned the same workunit will return the results more slowly than your machine. So, statistically speaking, if you have a fast machine, you’ll have to wait longer after crunching a workunit than someone with a slow machine, before your results are validated and you get credit.