Basically everytime you change something on the excel spreadsheet it does two things.
1- redisplay the screen changed
2- recalculate every single formula on the workbooks.
So the first option prevents the update of the screen until you have loaded all data,
and the second prevents the calculations to be done.
As for your sub-totals.
Whatever you do you need to load the data first, and only then do the group/totalling.
The only exception to this would be if you had to put the data on different places from the same record set.
e.g. records with fieldx = "A" go to worksheet "A", anb fieldx="B" go to worksheet "B", or something similar that could not be handled as part of the SQL.
I have a small Excel add-in that loads several files, combines then together into a final worksheet, and after this applies heading, deletes some columns, and groups/totals by group, and also sets some Page Setup variables.
All this is done AFTER the data is loaded.
Regards
Frederico Fonseca
SysSoft Integrated Ltd