Great! I don't understand what this means, though: > On i386 Intel Core2 and GHC 6.12.1, the improvements are > > alter 5.61 > delete 10.80 > difference 20.33 > insert 8.09 > intersection 7.69 > union 21.74 > update 7.96 What are the units on those numbers? What tests were performed to achieve them? Jim