Hmmm, the perl on that server was built without threads support (standard installation). So i doubt there were threads in that process :-) Also i discovered that the problem was happening when fcgi process reached max requests and tried to finish working. So perl just was cleaning up the memory. And you're right as far as i can remember the problem is occuring only on FreeBSD 7.X, not on 8.X. Thanks for advice, i'll try to upgrade the server to 8.X and monitor what will happen. :-)