title: Export DataTables into multiple Excel worksheets
body: <p>I've got a load of DataTables that I want to export into several Excel worksheets (in a new spreadsheet / Excel file). The "solution" that already exists in the code I have is two nested <code>for</code> loops, iterating over all the rows and columns, inserting data cell-by-cell. This isn't ideal as the process takes well over 10 minutes. There's a fair amount of data as the resulting spreadsheet is 8.5MB, but surely there must be a faster way?</p>
  
  <p>I'm using the Office Interop libraries to do this; I think I remember reading somewhere that you can import CSV with these. If this is the case, would it be quicker to turn the DataTables into CSV and then import this into Excel, and if so, how?</p>