David,
Our II file is 43 GB. When I open a chart with about 100 labs (and we don't have too many like that; by the way, I am counting the labs brought in on the interface from a single date as one item, even if it is multiple lines of labs)... it takes a second or two. This is not dramatically different from a new, empty chart.
So the issue is not the size of your II file, nor is it the number of items in a given chart.
It is hard to compare apples to apples because we use a peer-to-peer set-up, with a mix of Win7 and XP machines, with no SSD's. I believe our network is far smaller than yours (we are only two providers).
I have never been able to understand why some have this issue and others do not.
