I have sort of the same problem on my Windows 10 setup with 32GB of ram with a GTX 1050 TI (Lenovo Legion Y530). A couple days ago I was going to work on details on my painting and bumped the resolution up from 4000 to 8000 pixels. A couple of minutes after that the computer slowed down to a crawl and memory allocation whent from ~3.5GB to 27GB. I was working with a small amount of layers, about 8. This problem is not a new problem for me. I've had this problem as long as I can remember in AP. I'm not trying to be rude or be a wiseguy, but are you sure you are handling system resources the right way on the Windows plattform? MacOS version does not suffer from this and do not rush memory allocation when I increase the resolution of my canvas and layers or using a huge amount of large textures. AP is my daily driver at work eight hours a day and I love it. I use AP on iPad, Windows and MacOS.