Excel in Office 365 extremely slow (more detailed)?

I had formulated the question recently, but it didn't seem to be detailed enough.

If I want to start Excel, it takes 2-5 minutes before the program opens at all, regardless of whether I select an existing file or Excel in general.

If a table is then open (even the simplest tables without formulas), every action such as marking a field or opening a tab takes up to a minute. Even manual entries take up to 30 seconds before the font is displayed.

I have already tried:
- 1 x system newly installed
- 3 x Office newly installed
- Various troubleshooting

Important:
All other office programs run perfectly.
In addition, the same 365 Excel works perfectly on my laptop.

Sounds like too little system resources. Probably memory.

At first I thought so too, but I have 2 x 8 GB DDR4 3200 in it… Especially since gaming like CoD and Co works wonderfully.

Take a screenshot and print it out, send it to the Microsoft branch in Microsoft with a description and, to put it mildly, the tone is certain, after all you have 100 customers and have to prepare important accounts and maybe even that you will make claims. You could fall over several hundred thousand if it comes up.

Send your registered email with your name and contact details, especially your email address.

You won't find an email address from them, except: piracy@microsoft.com

Can't go that way, is a case for consumer protection if you can clearly prove that the cause is Excel and not your scrap box of… Current GamerPC.

The alternative is OpenOffice Excel, but that's just not MS Excel.