Sometime Crystal will pull all of the data into memory and then do the joins and/or filtering there. Here are some of the things that can make this happen:
1. Combining tables and a command or more than one command.
2. Using a command, but putting the filter in the Select Expert instead of in the Where clause of the command.
3. Using Crystal formulas in the Select Expert.
4. Connecting to a non-Client Server database such as xBase, Paradox, FoxPro, Access.
It can also appear as if this is happening if all of your data is in group header/footer sections and not in details, but there are few groups and lots of details in the actual data.
-Dell