Just wanted to post information that others may find useful. We have found that some of our very large Excel models take a long time to calculate in Excel 2002 (XP). Models that take about 3-4 minutes in Excel 2000 can take over an hour. However, this gets stranger in that this problem only happens the first time the model is calculated after many changes. Subsequent calculations finish in the regular short time period.

I believe this is related to the dependency tables Excel uses to figure out what gets calculated. Most of our models always display "Calculate" in the status bar, even after calculating, because their formulas exceed the 64K dependency table size (see MS KB article on this). The slow calculation may also be related to an interaction with the VBA programs that we use to iterate through hundred of recalculations.

In any case, the problem was present in the initial Excel install and with SP-1. Happily, the problem seems to have disappeared with SP-2. So, if anyone is having similar problems, I suggest you try installing SP-2 and retest. SInce I am in a large corporate environment, it was a pain to get an SP-2 update that works on our admin install (updating from the MS site won't work), as our IT group usually taked six months or more to test and release updates. It was well worth the nagging I did to get this. You can also try testing your model at home on the current release, then bring this evidence to your IT group to make your case.