One of the major differences between Excel 2007 and 2003, it that the maximum number of rows has increased from 65, 536 to 1, 048, 576. The maximum number of columns has increased from 256 to 16, 384.
We have to assume that at some point a user will try to compare two spreadsheets containing a million rows. I compared two sample spreadsheets each containing a million rows with a slightly modified copy of DiffEngineX (Version 1.27). A computer with 3.5 Gb of physical memory was used.
DiffEngineX can compare a million rows in a time measured in minutes, not hours. However the actual insertion of a blank row in order to line up existing rows requires DiffEngineX to make a call to Excel. This is intrinsically slow and so there may be pathological cases that will take longer.
I should point out that for most users a comparison of even a million rows should take minutes. If it is taking hours then it is a fair bet that the user is missing out a step. If you are comparing rows of data, as opposed to formulae based models, then you must get Excel to sort your data first in both workbooks. Sort functionality can be found under Excel's Data menu or tab. Then re-save your Excel workbooks. When you start up DiffEngineX make sure the Align Rows box is checked.
I should point out that a prior sorting step is not always needed. DiffEngineX will insert blank rows to get existing rows to line up (and therefore not be flagged as different), but it will not reorder rows. That is why they must be sorted first. Data imported into Excel from databases and third party applications will likely need sorting first. If the data originates in the form of Excel workbooks, it probably does not require sorting.
Please refer to the below tutorial for full details.
Tutorial: How to Compare Two Excel Lists
