Frames Droop

Hi everyone,
I hope someone can help me, because I'm going crazy...
I have the latest version of Premiere Pro, 26.2.0 (build 65)
My computer is a Ryzen 7 3800X with 32 GB of RAM and an RTX 5070 Studio 595.79, with SSDs, all running Windows 11 Pro 10.0.26200. In theory, based on all the benchmarks I’ve run, the system should be more than capable of handling Premiere Pro quite well. Well, with any video, even at 1080p, I experience constant frame drops in the preview when I import it into my project. This makes it impossible for me to edit any video. I’ve tried everything—using proxies, clearing the media cache, reinstalling Premiere, reinstalling the NVIDIA drivers—nothing fixes it... What could be causing this? I don’t know what else to do... By the way, I’m a bit of a newbie at this, but I’m a computer scientist and I can handle complex tasks.
Thanks in advance to everyone...