Sorry, I don't know what you mean by "additional linefeed in the info panel display." If you're referring to the line height, I doubt there's any way to change that. It does, of course, vary with font size.
In any case, you should do better using expressions to combine and manipulate fields. That can include tricks like turning a list into a string. For example, I have a list field [a.Moods], where a "mood" is generally a single word, and it's not uncommon for 20 to be assigned to an album. That's a little tedious to view in Theatre View, so I change it to
Replace(Replace([a.Moods], //, / • ), ;, / •)—a string with the words separated by "•".
It should also be possible to combine a group of similar fields (e.g., those fields you don't like seeing the "additional line feed" between) into one memo-like field for more compact viewing. Unfortunately, I don't know how to include a line feed in an expression (i.e., so each field, possibly with a caption, still appears on a separate line within the memo field). Maybe someone can help with that...