The Lightroom system requirements say 8GB is the minimum amount of RAM, and your PC meets the Recommended amount of 16GB. So memory is probably not the problem. However, some of us think 16GB is the real minimum, at 8GB some features or some larger images will edit more slowly. Personally I like 24GB or more for Lightroom.

A web search says your CPU is about 4 years old, that's relatively recent. But the one thing missing from your system specs is the GPU, what kind is it and how much graphics memory does it have? My guess is that it has Intel integrated graphics, and we’ll soon see why I think that…

I don’t use the Adaptive Landscape profiles much, but I tried it on three devices I have.
On a recent MacBook Pro laptop, it works pretty much instantly.
On a 5-year-old iPad Pro tablet (so, older than your laptop), it takes a few seconds for the thumbnails to show up, but once they do, the profile applies instantly.

But here’s the interesting one…I also have an old 2018 MacBook Pro with a Core i5 and 16GB RAM, similar to your computer. On that one, the Adaptive Landscape thumbnails take a few seconds to appear. When I tried to apply one, what I saw is what you saw:

That’s exactly what happened to me. The blue line got stuck near the beginning. I heard the fans spin up, so I checked processor usage and while the blue line was stuck, Lightroom was using most of the CPU power without anything happening. I waited a while for it to finish, then gave up and just quit Lightroom. It’s interesting that I see the same problem with a Core i5 on a completely different hardware platform (Mac, not PC).

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So, there might be a problem specifically related to some older Intel Core processors, or maybe with older Intel integrated graphics. You might consider filing a bug report for Lightroom in Adobe Community.