We should never ever complain about the quality of Apple software. I’m currently battling with Microsoft Excel which beachballs on multiple Macs just moving between adjacent cells.
I don’t understand how this kind of rubbish isn’t a solved problem. It’s just software.
I faced this issue. It’s due to you having software which also monitors the clipboard such as Keyboard Maestro, Alfred, Copied etc. - just put Excel into each of these programs ignore list and you are good. Somehow they are contesting to get Wxcel stuff to write into memory.
Office (all apps, not just Excel) ran terribly until I put an SSD in my Mac. I don’t know if that helps you, but that upgrade certainly fixed a lot of the slowness I had with office.