This type of thing leads to some of the most annoying UX regressions with "as you type" autocompletes I've ever seen. It's one of the reasons why I don't understand as you type suggestions. Either the person knows what they want and you should let them finish typing, or they don't, and there are way better ways to allow them to signal you they want a suggestion.
One of my earliest QA moments was how some of the women in the office could type so fast, our auto complete widget would spaz out.
I remember back in the day (like 90’s) there was significant latency noticeable on Macs when typing. Today if I have any problem with my hardware keeping up with my typing, it’s probably radio related. My Logitech MX Keys will stop buffer and then barf out a crap tone of letters, sometimes more than just my backlog. Not sure what that’s all about but I understand others have had similar problem with the keyboard. It’s not frequent enough to give up the otherwise great keyboard, and it’s worse over Bluetooth than Logitech’s wireless protocol.
I didn't read the whole thing, but of course this can happen and for a multitude of reasons.
Macs seem to have some weird input latency that I don’t notice on Linux or Windows. Letters don't appear for sometimes up to a full two seconds after I type them on my Macbook Air if I have an external monitor connected.