Again, these are micro-benchmarks designed to amplify the signal in various respects, and the numbers don't tell everything -- far from it, in fact.

As mentioned before, one of the most important aspects of a data structure is not just how well it performs itself but how good neighbour it is: the less memory it uses and the better its locality of reference, the less negative impact it has on other objects and data structures. However, these effects can be difficult to measure correctly, so a lot of the tuning and assessment have to be done by indirect means.