As a more programatic solution based on Walter's suggestion: If you're in a recent release (I think 18b), you can provide the 'UseExcel' parameter to disable communication with the Excel process. This generally speeds up writing since Excel likes to inspect the data and "do things" like evaluate formulas and try to convert text to dates as you write the data.
In general, I wouldn't suggest Excel for storing large datasets, but that really depends on what you're doing with them and what data you have.
Without any more context, my reccomendation would be to use CSV. It can be read by Excel, and a lot of other software as well.