Why is Microsoft deliberately slowing down FFXIV with updates and how to combat it?

[ItMe]

Ever since around December 2020, every time Windows 10 installs Windows updates, FFXIV loses a great deal of performance. With every Windows update, FFXIV ran slower and slower.

Windows 10 installed updates yet again last night and now FFXIV lags so bad that it is literally unplayable.

I had this.
I was regularly playing with about 7-9 frames a second.
If your situation is anything like mine it means your PC is ready to kick the bucket big time and I encourage you to get a new computer.