Not sure why you were getting downvoted these are pretty reasonable comments. The database example and use of B-Trees you mentioned is a good one. It’s definit

Not sure why you were getting downvoted these are pretty reasonable comments. The database example and use of B-Trees you mentioned is a good one. It’s definitely possible to create a performant and portable document specification and others have. I just strongly suspect that the performance issue that libre office and others have is more of a manpower issue and not having equivalent resources and knowledge of the excel formats rather than some shortcoming in ms’ own file formats.