The evidence for this supposed performance hit is basically zero.
If you compare a game that's had significant performance patches over a period of years and had Denuvo removed to the launch version (as so many of these videos are) then no shit you see performance differences, but it doesn't tell you anything.
This channel has many comparison videos like this one.
Loading times and 1% or 0.1% low FPS are usually hit the hardest and those stutters are the most immersion-breaking.