100ms optimization is a lot different for a CPU or a human brain. I'm not defending having the entire system log dumped out on every prompt but a few amenities are worth a few milliseconds computation time for a human.
Besides, I don't see how, for example , having your prompt take those 100ms to print a git branch or status breaks your "flow" yet having to type out the commands yourself and taking longer doing it doesn't.
Its a balance between bloat and and usability like so many other things, but, to me at least, being on either extreme of bloat or extreme-minimalism seems counterproductive.