ActiveX is, in fact, the only way to save your data to an Excel file. I'm not sure why it would be slow. Reading the data from your GPIB instruments should actually be a lot slower than using ActiveX to write this data to an Excel file. You might want to consider the
Report Generation Toolset for Microsoft Office if you are going to be doing much programming with Excel. This still calls ActiveX (as we said, that's the only way) to control Excel, but it prevents you from having to do it yourself. Everything is built in, so it's transparent to the user.
J.R. Allen