Word 97 also has a memory requirement of 8 MB. That legacy win32 code is extremely optimized, programmed in a time where every bit and byte was considered. It's today's background services and applications that slow Windows down, consuming memory and cycles for no apparent reason.

Office apps have also become much slower and less stable since they integrated cloud support and bolted on javascript for the user interface.

I'm pretty sure Office 97 was the last version to not use ribbons or have auto-arranging menus. As a support worker, nothing was worse than those two items. Having to walk someone through clicking a series of static menus was so much easier, could even be done in a doc with optional graphics, and the user might learn something in the process. After those things, there was no standard, anything could be anywhere, and there was no guarantee you or the user would know where to find the thing you were looking for. And they called it progress.

I had the same issue with slow loading office at work. If you check the network request, office opens 10 or even more connections on startup, i guess at least one is for licence check, possibly another one for one drive. However one of the requests took more than 8 seconds to complete, and during the whole time office would just sit idle.