Probably not since Easyminer really is just a pretty GUI interface that runs BFG in the background.  As for the pool side, thats just an estimate on your hashrate depending on the amount of shares you submit during a snapshot time period (usually like 15 minutes). So if you turn out some lucky shares/solve some higher difficulty shares/the pool isnt reporting shares and needs to catch up then that can be affected (I have had my Jalapeno clock in at nearly 20GH before because the pool took a while to record all of my shares that when it did it seemed as though I was hashing at a much higher rate).