I got a reply from Daniel that lftp compiled under Panther still works under Tiger, and doesn't have the CPU usage problem. I tested his Panther binary and I can confirm it indeed still works without problems.
So thats solution 1. For the real problem, I think I have found the culprit. The native 'poll' function in Tiger is broken. For more information the bug is documented at: http://bugzilla.gnome.org/show_bug.cgi?id=302672 >From what I understand of the documented bug is that Tiger now has native poll function and doesn't define _POLL_EMUL_H_ anymore like in Panther. But the poll function is actually broken in Tiger, or doesn't work properly under certain circumstances. The configure script of lftp doesn't know it is broken, but just sees there is a native poll function available, so it wants to use that instead of the emulated poll function. But when you compile lftp with Tiger's native poll function it will result in an infinite loop and keeps calling the poll function which in turn causes the heavy CPU load. (i used ktrace to confirm it) So for solution 2: You need to force the configure script to use the emulated poll function, I'm not sure if this is the easiest way but I used the following commands to accomplish this: $ tar -zxvf lftp-3.2.1.tar.gz $ cd lftp-3.2.1 $ sed 's/poll_works=yes/poll_works=no/' configure > configure.good $ mv configure.good configure $ chmod +x configure $ ./configure --with-openssl=/usr/include/openssl && make When its done compiling you have a fresh build of lftp using the emulated poll function and doesn't eat all your CPU cycles :) I hope this helped.