Since I've programmed JS before CS was created, I've long been resigned that I'd have to understand and follow the idioms of both languages. But using CS is so much sweeter to read and write that I end up being lulled into thinking that I'm writing Ruby. I can't tell if my brain is taxed more at having to switch between Ruby and regular JS, or if it's more tiring to constantly remind myself "this is not Ruby. This is not Ruby. This is not Ruby" while writing long stretches of CS :)

But I've only dabbled with CS so I'm sure like with anything, practice reduces this mental fatigue. I am bummed that CS went to camelcase, but the justification back then was a good one