Clojure devs: 3.5 is the figure you are looking for, and it does look very good, at first glance.
"Speedups Compared to Clojure’s Maps: In every runtime measurement CHAMP is better than Clojure. CHAMP improves by a median 72 % for Lookup, 24 % for Insert, and 32 % for Delete. At iteration and equality checking, CHAMP significantly outperforms Clojure. Iteration (Key) improves by a median 83 %, and Iteration (Entry) by 73 %. Further, CHAMP improves on Equality (Distinct) by a median 96 %, and scores several magnitudes better at Equality (Derived). Speedups Compared to Clojure’s Sets: The speedups of CHAMP for sets are similar to maps across the board, with exception of insertion and deletion where it scores even better."
Interesting indeed!
If qsort only provided a constant ratio time improvement over bubble sort in the average case, then it wouldn't have been so popular.
In reality other things matter.
However, it is still a meaningful incremental improvement over Clojure's implementation for iteration and equality checks, among others.
I wonder why the improvement wasn't adopted yet by the Clojure and Scala communities.
The CHAMP data structure was already picked up by the ClojureScript community (https://github.com/bendyworks/lean-map), but still requires some work to be upstreamed to Clojure I guess.
I personally (I'm the author of the thesis linked above) plan to work together with the Scala folks at Lightbend for the collections overhaul that's planned for Scala 2.13 (see https://github.com/scala/collection-strawman).