Thank you guys, but you are both wrong. Easy to explain. My room temperature here is 24C and when I use hardware monitor tool, I see that my CPU runs at 27C in normal work and it goes to 30-33C when I push it by some software. The same situation is with GPU which runs good with 33C, but with some video or graphical stuff it goes to 37-40C, which is acceptable. That means, running Windows 11 on my configuration is possible.
I know that Windows 11 has a problem with handling AMD CPUs, because of poor programing for "First Core Priority" stuff and handling L1, L2 and L3 cache, which probably will be solved in future updates.
If we speak about Firefox 115.0.2 only, then problem is with its poor software implementation for hardware acceleration of graphical or video contents. I see that when I open Event Viewer, go to the time of hang and see message that Firefox stopped responding, because some file is missing. It does not say what file, I can guess it, since it is related to files necessary for implementation of hardware acceleration for video content. As you probably know, but I will repeat it once again, that purpose of hardware acceleration is to use GPU for handling video content and to release CPU as much as possible, which is thing we all want. If I turn off hardware acceleration in Firefox settings, there is no hangs at all, but CPU will take over implementation of video content and that makes it work on 40-45C, which for some people is acceptable, but for me it is not.
That is the reason I think Firefox needs to make some update for better implementation of hardware acceleration for both AMD and Intel CPUs and GPUs, although they had that problem in November 2022, which they said it was solved, but it was not. The problem remains.
I am not the person who will invest some money to buy new more expensive computer in order to use Windows 11 (and I think I belong to huge majority of people who share this attitude), since it can be used on older configurations, like my 10 years old laptop, which runs an old Intel Celeron, with 4 cores CPU at 1.6Ghz. And guess what? Hardware acceleration inside Firefox works properly and there are no freezes of computer because of it.
It is poor software implementation of Firefox in this particular matter as well as it is poor software implementation of Windows 11 regarding handling AMD CPUs and their multi-core environment. I asked for some fix (although I thing there is no any of possible fixes) or we need to wait for Firefox to solve it in the future updates.