This is a wonderful module and system. I've been using drupal for a few weeks and love it.
I'm developing a financial analysis application and it has a good amount of fields. In one create content node, there are:
37 data input fields (not that many if you were doing a survey)
23 simple calculated fields (add field 1 and field 2, divide by 100, etc.)
12 calculated fields based on calculated fields (add three previously calculated fields together, etc.)
all running smoothly. until i started getting a "division by zero" warning upon saving a node. I can see in the display that a number of calculations are not complete (still zeros). Now, if i just toggle back to edit and save again, the form completes fine w/out errors.
Later, if i change a number, i need to save, toggle edit again, and save again for all the computations to take place.
I've started deleting fields going backwards to see where the limits are but i'm now well smaller than when it was working a few days ago.