I've been experiencing this problem in Lenny myself. I use unencrypted, remote X, using XDMCP to establish a connection. I find particular problems when using Evolution - it's unusable to scroll the lists. I also experience slow performance using X tunneled via ssh.
I've applied Stephane Graber's patch for libxcb, which he created for Ubuntu. See the libxcb patch in: https://launchpad.net/~stgraber/+archive/ppa You can find my application of this patch to Lenny (for i386 only right now) here: http://www.wmltd.co.uk/debian/libxcb1/ This patch restores the acceptable performance I was experiencing in Debian Etch (prior to my upgrade to Lenny last week). I've uploaded all the files I edited there; you can download the .deb files and install (all of) them. The build tree is there, too. The patch is only a couple of lines. Hope it's helpful. Seb James -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org