Just throwing this out here. This is the old rule of thumb.
If the QVW size is 100mb on the hard drive and you are going to have 10 users the memory used would be around 800mb.
100mb x 4 = 400mb (this is just to open the document)
10 users at 10% (of above 400mb) will add 40mb per users or 400mb
This is without making selections. You will see the memory go up and down based on the clicks.