Time with check: real 0m10.595s user 0m7.156s sys 0m2.469s Time without check: real 0m9.848s user 0m7.186s sys 0m2.383s I did the test with the swbuftest version in cvs now. I disabled the output to console as it is an expensive operation. What do you say? It looks like there is a real difference there. Should we disable the check? mg