1. In Excel I have 1 summary sheet that takes 2.5 – 3 minutes to recalculate. 2. It recalculates whenever I make any small change – unless I turn the Calculation option to Manual. 3. There are 10 other sheets in separate workbooks that feed different tabs in the summary workbook and then into the one summary sheet (some are .xlsx and some .csv). 4. I download all data into the various sheets from our major accounting/manufacturing application because that application does not provide for adhoc reporting. Most of these "other" sheets contain between 4,000 and 10,000 rows and 10 columns, 6 are transaction files (only 1 major), 2 are master files providing static descriptions, conversion factors, etc, 1 is opening/closing stock file. Am I over-extending the use of Excel and should be using MS Access or MySQL or some other database application. Anybody have any thoughts on this?