If the hashrate is too low poolside, increase the diff until you get rejects locally.
--diff 0.00390625 is the only setting that gets me no local rejects but only gives 1/10 the hash on the pool. All other diff settings in multiples of 2 or divisions of 2 give rejects and still not the correct hash at the pool.
if i increase the diff over and above 1.0 in multiples of 2, the miner starts submitting faster and faster with 0 accepts.