Something seems wrong with the difficulty . With stable hashing power climbs to 14M for 2 to 3 blocks and then down to 3M up to 6M and after 2-3 blocks back to 14M.
The stable hashing you refer to, is that on your pool or across the whole network ?
The Timespan is set to 12 * 60 and the Spacing is at 6 * 60