About the slightest impulses I referred to yesterday in addressing fingering: What we call "classical music" is all about slight impulses, really, as opposed to tunes that you whistle or the cliche reruns of your favorite Beethoven symphony.
There are basically two types. First and foremost is tone--not just what tone, but exactly how sharp or flat, how loud or soft, how begun and how ended. Tone is the fastest, slightest impulse--the one embodying the fleeting nano-second that constitutes magic to the small child and during which the mature musician makes countless decisions.
I put rhythm second because it is learned as motor responses and these are always slower, i.e., ploddier, than one's awareness of the magic of tone. Rhythm, customarily learned in terms of exercises and repeated patterns, readily obscures tone and quickly leads to boredom.
So what if you can play fast and are not really paying attention to those slightest impulses?