Open large files quicker

Good day good people!,

My last thread had not been answered, so I would imagine it's mission impossible. . So, I am left with one option, and that is to generate random numbers and do some calculations in about 25 columns down to 1000 000 rows, to hopefully get a specific combination. All of this is in place. I have actually split the workbook into 3, and have about 10 columns in each down to row 1 mil. I was thinking that this way the 3 workbooks when opened one by one, would save a lot of time. It only works for workbook 1. Workbook 2 still takes a looong time, not to even talk about workbook 3, to open. I have searched, honestly, and found answers about copying into R (What is that?), and some codes that also do the trick to help with opening large files quicker. I simply do not understand how to make changes to those codes to fit my requirements, so I'm humbly asking anyone to please help me with, I presume a code, or any other method, to assist in opening these files quicker. The file names are Book 1, Book 2 and Book 3. As usual I appreciate and receive all and any help with great admiration and gratefulness. Thank you..

Hallo Michson, uploaded...thank you for your time spent on this..