Ah, I see now... I didn't realize that this was end-user data via Google Toolbar opt-in. I've got "medium accuracy" 100-1000 data points, and I'm assuming that

Ah, I see now... I didn't realize that this was end-user data via Google Toolbar opt-in. I've got "medium accuracy" 100-1000 data points, and I'm assuming that means total over the full 5 months. In that case, it doesn't surprise me that some combinations of visitors and connections might have long load times. But yes, the fact that non-visible elements seem to make a difference is not great.