miner slows down?

[corvox]

I have noticed while mining at first I fly threw to about 280/280 accepted. then after that it really starts to slow down, instead of 1-2 per sec, I am only solving 1 every 10-15 secs, is this normal?

If I restart my miner, it does the same thing, flys for the first 300 or so accepted then slows to about 1-2 every 15-20 secs.