tp34
ext4 on an old system, feeble in comparison to yours, performs much better.
ext4, 8GB memory, 2 core Intel i7-4600U 2.1GHz, Toshiba THNSNJ25 SSD:
$ time ls -U | wc -l 555557
real 0m0.275s user 0m0.022s sys 0m0.258s
stat(2) slows it down, but sill this is not as poor as your results:
$ time ls -lU | wc -l 555557
real 0m2.514s user 0m1.126s sys 0m1.407s
Sorting is not prohibitively expensive:
$ time ls | wc -l 555556
real 0m1.438s user 0m1.249s sys 0m0.193s
Drop caches, sort, and stat:
# echo 3 > /proc/sys/vm/drop_caches
$ time ls -lU | wc -l 555557
real 0m6.431s user 0m1.249s sys 0m4.324s
I think you meant "there are fewer people." Were you home schooled? Perhaps public school English would have been a better option.
cgroups require code to implement. This is overhead. "Literally" is not the word you should be using. Perhaps "little" overhead or "minimal" overhead?
Assuming you possess this basic competence, I find myself wondering how you managed to purchase a vehicle with such absurd ergonomics.
You have a strange, poorly designed vehicle
This "big dashboard full of buttons." Please provide a picture. Is this a custom design?
"For me, when things get dangerous, its [sic] when pressing the button (physical or touch) doesn't do what its [sic] suppose [sic] to do."
What actions are you referring to? Changing the audio volume? The interior fan speed?
You may want to consider researching your vehicle purchases more rigorously.