How do the calculation settings work when you have multiple workbooks open? Is it set at application level?

My problem is that i have a developed large spread which needs automatic calculation to be disabled to run quickly.. However, i find that if i first open a workbook that has automatic calculation enabled, that all other workbooks i open will run the same setting?

If the above is correct, is there any way to force excel to use calculation settings at file level instead of application level?

I want to force excel to disable calculation on this workbook, but should not 'overwrite' the calc settings of other workbooks that a user may have open.

Vincent