I've noticed, that on w10, there is actually a memory leak in 'system'. As in, if PA is kept running for a few hours, the 'System' entry in task manager slowly increases in memory. In the end it was using more memory than PA. When I close PA, it goes back down to a reasonable amount. It seems like my graphics driver leaks.
It could well be the fact AMD and nVidia haven't gotten their Windows 10 drivers fully sorted just yet
OpenGL can actually allocate host memory to back up texture and vertex buffers (the driver is free to do this depending on the usage hints, or anytime it feels the need for it). I'm not sure if those buffers count against the application or is something that counts as system resources.
"System" process memory use rising with apps is quite normal. Especially if your physical RAM preasure increases. The system process is where paged and cached memory are monitored so they count toward that total. Bad news is that the new Nvidia driver did not help with my extreem memory use spike crash. I guess I may be suffering the w10 memory leak mentioned above. I also tried disabling SLI for PA as I have noticed a few other games like planetside 2 not working well in SLI mode on w10.