defaults write com.apple.Preview kPVPDFDefaultPageViewModeOption
this setting is the same as "Opening for the first time" setting in PDF pane of Preview's Preferences.
0 Continuous Scroll
1 Single Page
2 Two Pages
It didn't work for me in macOS 10.15.3 (19D76) as change this setting doesn't affect fullscreen PDF display mode. And I doubt this would work ...
The number appears to be coming from the program top. I found the following blog post which investigates this calculation in much more detail: https://blog.mozilla.org/nnethercote/2015/08/26/what-does-the-os-x-activity-monitors-energy-impact-actually-measure/
In every case, Activity Monitor’s “Energy Impact” was the same as top's POWER measure. Every ...
I wrote an applescript, I normally run it from the terminal but it could be easily modified for some other ease of use that suits you.
Output shows window/tab, title, memory used, URL
With long strings shortened to start...end
To get the memory size you will need tabs showing process ID as detailed by several posts above.I use a function to run the script ...