How many times slower, the fastest benchmark programs for selected programming language implementations are, compared to the fastest programs written in any of the programming languages.
Notice which boxes have no overlap; notice which boxes overlap completely. Notice which show little midspread; notice which spread across too large a range of values for confidence.
You can see that the order would be different if it was based on the median scores instead of the geometric mean scores.
The boxes are broken into separate groups, at the minima of the kernel density estimate for the geometric mean scores.