Hi Slurt, properly configured LXDE should be quicker than Gnome. You may be having issues because Lubuntu is still in Beta testing for an official release in October. Try a stable LXDE distro like SliTaz or Debian Lenny + LXDE and I think you will be pleasantly surprised.
If you post your hardware specs maybe we can suggest a distro, or a tweak to get Lubuntu working better. It is impossible to give specific advice knowing nothing about your hardware.