How can we compress a big excel worksheet or files?

Great question.

I will give you a one million dollar answer.

1. remove all the redundant format for unused cells (big save here)
2. remove all unused cells.
3. remove unused shapes, charts, pictures.
4. change formulas to values (that will improve the speed). you can keep that last row formula (good idea ha)
5. done.

thank you for the question

i did that before but the problem is to convert the excel sheet to another form then reconvert it to an excel sheet .