I've been investigating the performance of some word frequency counting code I wrote, and I came across this stackoverflow thread http://stackoverflow.com/questions/3058529/curious-about-the-hashtable-probl... Dons shows simple benchmarks for HashTable and IntMap, but I can't reproduce the "after the fix" performance of the HashTable code, I am very confused as to what version of ghc actually has the fix. In the post Don writes "With GHC 6.10.2, before the fix, inserting 10M ints:" and then "With GHC 6.13, after the fix:", is this a typo, shouldn't it read 6.10.3? Since there is no 6.13 version of ghc yet? If it should be 6.10.3, and I'm running v 6.12.1, why does the HashTable code in Don's post take 22 seconds to run on my machine (compiled ghc --make -O2) and the IntMap version takes only 5.8s? How can one find out what release the fix for ticket #650 was released into? I've tried the release notes but I can't seem to spot it, and google doesn't either. The ticket has "Milestone: 6.12.2" but that is struck-through, though the comments would suggest this made it into r 6.12.2, I can't spot anything in the release notes for that version either. Can someone help clarify which version the fix will be/is in and how one should figure this out in general for other issues? Thanks Tom