To be honest, I have not come across many reports that are that bad as this one regarding Win10 to Win11 upgrades, but I have no reason to not believe you. “In-place” Windows upgrades are almost always tricky, there’s just no knowing what small thing might undermine the whole process.

It does sound like there’s something seriously wrong with this system, like a driver or setting that does not sit well with this new Windows version. More than a minute of booting on even a mid-range SSD is just not OK.

I do hope that a future update or several updates will fix this at some point. It may even be an update that does not address specific bugs — I have had that experience with Win10 twice already.