Branden, what terminal are you using? I would like to try the same. I guess Ubuntu is quite close to Debian in that respect.
1. I tried different terminals and even SSH.
2. What modes can be relevant?
3. I never heard of any relevant configuration options of bash. What could it be?
Also "stty" settings are OS-standard.
Control-V does not have any delay. It just quotes the next character - whatever and whenever it comes. Even if I input that after an hour; no matter if it's just ESC or an escape sequence.
So this is not helpful here.
I can easily imagine that the whole escape-sequence may not be available for the reader right away, depending on the terminal, modes, etc. For example, with limited baud rate the sequence will always be read by one character.
But I am pretty sure there is no any significant delay between the characters. Not even 1ms.
There is also a possibility of some custom build settings or patches in these OSes.
Readline version here is: 6-6.3