Stale shares are around 1-2%. Of course there were many stale shares in this round, but it is how it works. Calculating stale shares is not fair, because people get reward for something which cannot give valid block to pool. It also improved overall pool performance, because some people had strange miner settings (ask rate over 180 seconds etc).
I'm not advocating counting stale shares but I was curious how many stale shares arrived within the same timeframe. It can show the delay inefficiencies.
So 7 seconds for three shares at the beginning of round seems to be fine.
I would expect more. With 5s getwork refresh time, most of the workers should have worked on the non-stale block at least some of their time. Some of the workers should have worked most of this time. Only 3 shares is below 0.5s of the pool capacity. I would expect 10-20 shares.