Let me explain. Pool software has a whole set of cron jobs scheduled to run at a regular intervals of time. If even a small error occurs, pool automatically disables corresponding cron job. That's what has happened with vtc.poolz.net, at 6:31 AM EST the following message has arrived:
Error Code E0062
Error Message Block has no share_id, not running payouts
The problem was with the block number 29921. After that, blocks were being found but were invisible because of disabled cron job, responsible for accounting of newly found blocks. I woke up around 11 am, investigated the problem and fixed it. After that I enabled the cron job previously disabled by the pool sw. Blocks found during the time when the cron job was disabled got accounted and paid and now you can see that in fact from 6:30 to 12:11 we found 11 blocks.
Till the last time we had efficiency of 80-95% (means that we managed to find more blocks than we should in average). Last day our pool experienced multiple DDOS attacks (and other Vertcoin pools too). I spent lots of time and almost a whole night trying to mitigate these attacks (currently we have mod_evasive enabled only which helps to some extent), and our pool soon will be moved to a data center with AntiDDOS support. Because of the DDOS attacks our efficiency decreased a little bit, but I hope that we will catch up.
So in reply to the: "I think the big mining rigs have caught up and learned how to compile and tweak Vertminer", I can't say anything about other pools, but this one is not stealing your money for sure. 1% Pool fee gives me a bit more than my mining rig, but I'm spending more time to maintain it, compared to my mining rig. In the last 2 days I upgraded server powers twice - and now pool server's hardware allows to accommodate 5 times more miners than current amount.
Guys, I'm on vtc.poolz.net. They have 10% of the mining power, but haven't found a block in a few hours. Next difficulty is estimated to be 189! Network hash rate is 5.2Ghash/s and climbing, which gives this coin a 10.4Ghash network in LTC Scrypt terms. I think the big mining rigs have caught up and learned how to compile and tweak Vertminer.
I'm still mining with you, mate. You have navigated the explosive growth in the network extremely well. Thanks.