Vimtutor doesn't muscle memory everything in. But it does muscle memory in basic things such as deleting, moving around and going to beginning of lines, enf of lines etc.

That's what it did on my first run. It indeed wasn't perfect, but there were already a couple of tricks that I've learned that I really liked and that's what you get out of it.

I'm not saying you work faster, I'm saying after vimtutor you won't work slower.

I suppose you still work slower if you compare it to your favorite text editor, I'm not very strongly proficient in any text editor, which is why I'm not noticing slow downs.