Syntax Highlighting Off

I find that comments at the top of functions are helpful when implementing an algorithm found in reference material, especially if they have a citation. At least that way you can check that the function appears to do what the reference material specifies.

But generally commit messages, descriptive symbols, simple logic, short functions, and unit tests are better.

I find syntax highlighting is brilliant for focusing on small elements in code. Switching it off is useful for looking at the overall structure of a closure.

Agreed, it also depends on what you're trying to do. If you have time to read and comprehend each and every line of code then that's obviously ideal, but time is the most precious resource we have. I find properly implemented syntax highlighting provides a "visual outline" of the code which I can use like a table of contents or index. This allows me to save time and focus for the segments of code that require my full attention. Sure it makes things more "jumpy" and sometimes I have to backtrack to get context, but I find it makes the overall process much more time-efficient.

I'd also point out turning off highlighting may produce a false perception if the color scheme you're switching from is mediocre or worse (as most of them are in my experience). To a starving man McDonalds tastes like heaven. Properly implemented syntax highlighting shouldn't be distracting in the first place. If you're using syntax highlighting and have trouble reading code line-by-line then that's just a sign you need a better color scheme IMO. I switched from some random theme I found online to solarized-dark a couple of years ago and found it made the reading experience much smoother.

At any rate I'm glad he's found something that makes his programming more productive and enjoyable, but I would avoid categorizing it as objectively better, as the author tries to do.

I don't understand the reasoning behind this. What possible benefit could you get from turning off all syntax highlighting?

It's useful to distinguish between language keywords and user specified names. Being able to visually ignore one of them, while focusing on the other, is a tremendous benefit. It cuts down the number of things you need to hold in your head at once, by half.

It's useful to distinguish between local variables and instance variables. It helps to better understand the dependencies that exist between a method and other methods/state.

It's useful to distinguish between mutable variables, and constants. It tells you at a glance how something is being used, and the pitfalls you need to watch out for.

Turning off all syntax highlighting destroys all of the benefits above, and I can't think of any notable benefit you would get out of it.

I guarantee you, whatever "upside" you think you're feeling right now, it's simply the novelty effect. This is a very common phenomenon in AB testing. Often times, you see an initial improvement, simply because users respond positively to the initial novelty of something being different. I guarantee you, if you continue to work without syntax highlighting for 6 months, and then turn it back on for a few weeks, you'll realize how much you actually love it.