Assume a constant difficulty.

Assume pool produces a new block every 30 seconds on average, for a particular coin and at the pools particular total hashrate.

Miner A has 0.5 megahash hashrate

Miner B has 5 megahash hashrate


Assume these hashrates translate to finding a share every 30 seconds, or 3 seconds respectively (again, on average).



Miner A will only find a share in time approx 50% of the time. So half the time he has 1 share, half the time he has 0 shares. He will have worked an average of 15 seconds for nothing when the block changes.

Miner B will find an average of 10 shares. He, as well, would have been working towards another share when the block changes. However, on average, he will have only been doing so for 1.5 seconds.

So the difference for Miner A is the difference between all or nothing.

The difference for Miner B is between, say, 9 and 10 shares... or maybe 10 and 11 shares...

Do you see it yet?