Find line-height parametre using "Inspect" and change it.
Inherited parametre value is 1.2 by default. If you change the value in Inherited from div#rstudio_source_text_editor (or Inherited from td, not sure), it will affect line hight for all panes.
Unfortunately, I couldn't find how to change the hight only for the editor, so I've changed the value for all panes, and then set it for Console and Files panes separately.
I hope, the screenshot will illustrate the process!
console_line_height_wcomment|690x413