That's interesting, because I've never noticed any flickering with my conky on any pc with Xorg with default or Nvidia drivers, or mac for that matter using the current conky in the tc-5.x repo
All my desktops, notebooks and VM's use Xorg now with the same old conky used since tc-5.0 (perhaps tc4.x or earlier)
An updated version might be welcome, though more importantly we probably need a recompile of conky for corepure64. My current version is Conky 1.8.1 compiled Thu May 19 12:24:14 UTC 2011 for Linux 2.6.33.3-tinycore (i686) in tc-5.2 (with Xorg, Xvesa)
I don't use buffers at all iirc (my conky conf attached)
Isn't double buffering enable via the conky.conf (conkyrc) and Xorg modules anyhow?