Unless you have the entier united states worth of surface area as a dedicated CPU the warning is very much still relevant.
You are asking the engine to query all actors for something.
First of, doing so every frame is silly.
Second of:
You are bottlenecking the usually desired frame time of .12 ms with less than 1000 actors to be checked just by computational execution speed of a comparison in c++
Sure, better CPUs with more surface areas will suffer less and less (hence a us wide surface arra cpu wont have an issue) but as CPUs increases and games get better, more actors get loaded, compounding your problem or keeping it just about the same.
And finally, the real question is Why.
What could possibly require to check all actors every frame?
If anything does, I can 100% guarantee the system and logic behind it are so poorly designed/thought out that even with the mentioned above CPU power you’d get issues with the project…