Wow, I was doing fine until the counting while reading in a different accent part. It felt so strange, like the gears had jammed in my brain.

I speak two languages fluently. I observe that it is slightly easier to count in one language and read in the other. The full ranking is reading without counting > reading English, counting Danish > reading Danish, counting English > reading Danish, counting Danish > reading English, counting English. That counting Danish > counting English is presumably because I don't count in English nearly as often. I used an LW article as my English text, and a physics textbook as my Danish one. I would say these two texts have similar difficulty.

Like bramflakes, I was surprised by how difficult it was to count while reading in a different accent.