Fee problems(the fee is mined in the first hour of mining):

mine 1 hour and quit: fee 12%
mine 2 hours and quit: fee 6%
mine 3 hours and quit: fee 3%
mine 4 hours and quit: fee 1.5%
mine 12 hours and quit: fee 1%
...

So if your rig is unstable and crash, restart every hour, 12% fee...


Gpu search high intensity problems

1. Searching 500 000 solutions in a low difficulty. 17 solutions found. spminer will only report 2 of them.
2. Searching 500 000 solutions and the pool change difficulty and reject your work.(stale share) you loose 500khash
3. Searching 500 000 solutions and the pool change block and reject your work. you loose 500khash
4. Searching 500 000 solutions and the pool restart your work. you loose 500khash (nicehash, zergpool and other multipools does this all the time)
5. Searching 500 000 solutions and the pool have a new job. you loose 500khash
6. Searching 500 000 solutions instead of 10 000 require more gpu memory and more power. Make sure that your cards don't trottle and and feed them enough power.

Spminer is faster in finding blocks.
 www.miningpoolhub.com and www.hashalot.net rewards the blockfinders and doesn't trow away the work in 2-5 that get rejected on other pools. As a miner you want to get payed for all your work.

Mining on a fixed low difficulty will hurt pool performance because solutions are skipped.

i have the same problem with GCN 1 & 2 i told SP about it,a few minutes into mining it starts submitting shares with a high ping due to lag, in my case even SP3 lags, what driver version are you using ?

I use the newest drivers. I have a Radeon Pro Duo in 4 different systems because none of the miners work right if I put 2 of them in 1 system. So I can install either the Pro drivers or the Adrenaline drivers. It doesn't make any difference however with Sp4.