It's not MY problem: just a user here, like yourself. Providing help isn't an "excuse." Proxies can speed up editing when dealing with large, complex content. https://www.descript.com/blog/article/how-to-use-video-proxies-to-speed-up-your-editing-process
While it's certainly your call and opinion, it's no "effrontery" to suggest using a lower resolution. Many folks work with 4K files because that's what their camera puts out. But IMO, 4K is oversold when viewed on typical monitors, and HD looks just fine. For theater presentation - that's something else.
A 1:09.00, 35GB, 99 file, 4K HEVC project with no effects or transitions was tested.
In VP initial caching took about :30. Play was smooth, but for some random buffering. AVC 4K export completed in 40:10 minutes. CPU was in the 2-3% range with GPU consistently at 75%.
AVC export completion in a competing editor came in at 82:38 minutes. CPU usage was in the 80-95% range, GPU max was 60%.
What video card/adapter is on your system? It can make a world of difference.
My PC's specs are similar to yours, so if you want a hand at tracking down slow performance, please submit the project as instructed above. Good luck.