  The tango tree is the first proven $O(\lg \lg n)$-competitive binary search
tree (BST). We present the first ever experimental implementation of tango
trees and compare the running time of the tango tree with the multi-splay tree
and the splay tree on a variety of families of access sequences. We construct
access sequences that are intended to test specific properties of BSTs. The
results of the other experiments demonstrate the optimality of the splay tree
and multi-splay tree on these accesses, while simultaneously demonstrating the
tango trees inability to achieve optimality. We prove that the running time of
tango trees on the sequential access is $\Theta(n \lg \lg n)$, which provides
insight into why the $\Theta(\lg \lg n)$ slow down exists on many access
sequences. Motivated by experimental results, we conduct a deeper analysis of
the working set access on multi-splay trees, leading to new insights about
multi-splay tree behavior. Finally, all of the experiments also reveal insights
about large constants and lower order terms in the multi-splay tree, which make
it less practical than the splay tree, even though its proven competitive bound
is tighter.
