Can anyone explain to me why I put about 4.2-4.5Mh/s, but middlecoin is only showing 3.5-3.6Mh/s? It's been running for a couple hours now :\
You could have high reject rates...
Or... hit F5 to refresh browser after you open all user stats.
Or... click on your payout link if you have been paid at least once already.
Also, it sounds stupid, however, make sure all your cards are actually hashing / getting accepted shares.
Sometimes a configuration will appear to hash / won't crash the system, however, if your Worker Units are significantly less than your reported hash rate, then you probably aren't running with proper settings.
On an even dumber note, I had a single card overheat earlier and it took a while to catch it, as the rigs are headless. Once I modified some thermal parameters and restarted, my hashrate went back up.