I have caught moments when my latency goes up from 150-160ms range to over 300ms, that may be enough to explain dips in my poolside numbers. I believe there is some kind of new problem with my internet, for the month before it poolside rate was quite steady.
restarts/reboots etc had not generally made a difference though past 2 days is somewhere in the middle.

[You just read marketing for cwi miner having the rare feature of showing live latency to pool ]