Is "server performance mode" enabled or not?
OK, I guess I have one way to determine based on What does serverperfmode=1 actually do on macOS?

If you take the output from sysctl -a you can search it for some of the items listed above and see what their values are.

sysctl -a &gt; temp.txt

Search temp.txt with your favourite editor and look for kern.maxvnodes, if it is 300000, and if kern.maxproc is 5000, then you are in "performance mode".

Or at least some of your settings match the "performance mode" settings.

Since I did both the NVRAM variable and the "disable SIP and use serverinfo --setperfmode 1" methods, I don't actually know if the NVRAM method by itself results in the changes for High Sierra.