I was wondering if anybody could explain why the rate at which I've been mining blocks seems so slow? I switched to another pool for a bit that works the same way and was mining blocks 10 times faster. I used to mine blocks/work from middle coin much faster than I do now and just wondering what's up with that?

The network difficulty is changing every 2 seconds right now but I'm getting no work/shares...the difficulty just went from 21 to 51 without a single share or any work sent to my GPUs. I guess shares is the correct term? lol, kinda newbie.