I saw a skilled vim ninja do this a while back but I have no idea were to start.
A) Is there a way to set up vims background colour so that consecutive lines with identical content get highlighted.
B) If somebody knows how to do that a nice tweak to this would be if the highlighting happened on consecutive lines but only consider the first word (not the whole line).
A second tweak if the highlighting could be configured to different colours are used based on the number of matching lines (or words depending on A B is active). So of we only have two consecutive lines that match then green, 3-5 consecutive lines then orange, 6+ then red.