Compare 95 cpl Times New Roman at 12 pixels to, say, 80 cpl Source Code Pro at 14 pixels. People are more efficient at reading at a certain cpl because the eyes

Compare 95 cpl Times New Roman at 12 pixels to, say, 80 cpl Source Code Pro at 14 pixels. People are more efficient at reading at a certain cpl because the eyes don't get tired (less movement) and it's easier to find the beginning of the next line (maybe I'm the only one who has trouble with that for long lines). Most of these factors depend on the typeface used, the font size, line height, and of course, the distance between your eyes and the medium your reading. When you're talking about code the syntax of the language probably plays some roles in all of this as well (Python is a narrow language, C++ isn't, JavaScript needs lots of indentation, etc.).