This is on MSYS2, yes, and that excuses absolutely nothing, because this shouldn't be happening in the first place for speed to be even relevant. At the risk of repeating myself thrice: the messages are confusing, the Ctrl+C handling is just utterly broken, the citation message adds to the confusion while being frankly obnoxious, and all of the delays and outputs are unnecessary in the first place as proven by literally every other program that doesn't make me wait a minute before I can use it the first time, including xargs. If Microsoft's own Windows tools did this, everybody would bash them (no pun intended) till the end of time. But since it's GNU Parallel and not Microsoft Parallel, it's Windows's fault for being slow and also my fault for having the audacity to expect better, apparently.

> the messages are confusing > while being frankly obnoxious

Try reading some time. It's pretty great.

> the Ctrl+C handling is just utterly broken

That's your terminal, not parallel.

> and all of the delays

Your terminal is adding the delay, not parallel. parallel is just warning you about your broken terminal. You're shooting the messenger here.