My input speed definitely is my bottleneck when writing down the code I have constructed in my head. So why not optimize this part of programming?
Same here. Never learned to type properly and this happens often enough. I can't count the numbers of times I thought 'man, if I'd just have a brain-machine interface which would tranlate my thinking into text this thing would have been done 10 minutes ago'.
And I have actively practiced my typing to try to reduce this pain. I am stuck at a sustained speed of about 55 WPM, much slower than think. In bursts I can get it much higher, but not for a whole C++ class or lengthy function. I know it shouldn't annoy me but it does that my father, who is practically retired and has has never coded types at like 80 and this while in the military of all the unlikely places.
When using emacs/vim and primarily using the keyboard, there are extra gains to be had by typing faster, because you can use keyboard shortcuts to navigate, find text, etc.
Unless you're playing a videogame, it's unlikely that you'll practice or improve on your mouse coordination and make significant gains there.