I've finally performed test on amd64 and result is a same as on intel. KMP always wins. So KMP is best suited for non indexed strings and I guess should be used in library as prefered search/replace method. This test favors straightforward search. [bmaxa@devel64 myhaskell]$ time ./KMP Working:seasearch replace able seaseasearch baker seasearch charlie True Done real 0m10.783s user 0m10.769s sys 0m0.016s [bmaxa@devel64 myhaskell]$ time ./straightforward Working:seasearch replace able seaseasearch baker seasearch charlie True Done real 0m11.769s user 0m11.741s sys 0m0.028s [bmaxa@devel64 myhaskell]$ uname -a Linux devel64.office.kom 2.6.14-skas3-v8.2 #2 Fri Nov 11 21:19:36 CET 2005 x86_64 x86_64 x86_64 GNU/Linux Greetings, Bane. _________________________________________________________________ Express yourself instantly with MSN Messenger! Download today it's FREE! http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/