XLSB is significantly faster to process because it does not require an XML parser to blast through the data. Numbers are stored directly as IEEE754 doubles. Text may end up larger because XLSB uses UTF16LE for everything, including pure-ASCII strings (since Excel uses that format internally, there is no conversion involved and XLSB still will be faster).
The problem you will encounter is that most programs (Numbers, Google Docs) do not support XLSB.
Shameless plug: https://github.com/SheetJS/js-xlsx supports both XLSX and XLSB (AFAICT the only liberally licensed project that handles the format)
The problem you will encounter is that most programs (Numbers, Google Docs) do not support XLSB.
Shameless plug: https://github.com/SheetJS/js-xlsx supports both XLSX and XLSB (AFAICT the only liberally licensed project that handles the format)