> “Faster” is misleading
and
> "At low levels there is going to typically be negligible or no speed gains, but at higher levels the benefit will be incredibly obvious."
there are no "speed" gains period. the same amount of work will be accomplished in the same amount of time with threads or async. async makes it more memory efficient to have a huge number of clients waiting concurrently for results on slow services, but all of those clients walking off with their data will not be reached "faster" than with threads.
the reason that asyncio advocates say that asyncio is "faster" is based on the notion that the OS thread scheduler is slow, and that async context switches are some combination of less frequent and more efficient such that async is faster. This may be the case for other languages but for Python's async implementations it is not the case, and benchmarks continue to show this.
“Faster” is misleading because the speed improvements that you get with async is very dependent on load. At low levels there is going to typically be negligible or no speed gains, but at higher levels the benefit will be incredibly obvious.
The one caveat to this is cases where async allows you to run two requests in parallel, rather than sequentially. I would argue that this is less about async than it is about concurrency, and how async work can make some concurrent work loads more ergonomic to program.