This is just not true. The only chugging back then was reading from disks, and the entire Office suite was only a handful of 3.5" floppies. If you had already started Excel earlier, then it was likely still cached in RAM and would start nearly instantly. If not, then it was still only a few seconds.

Now what was slow was actual computations. Like try running a big spreadsheet in Excel or counting words in a big Word document on that hardware. It takes a very long time, while on modern hardware it's nearly instant.