[span style=\'font-size:14pt;line-height:100%\']GIMP1.2.5[/span] is much faster on my SL6000 than any of the newer versions of GIMP I've tried. I use this mostly for handwritng.
Note that this version is built without support for perl or gimp-print, but other than that, it's the complete distribution.
[span style=\'font-size:14pt;line-height:100%\']gsumi1.1.0[/span] is essential the ink tool for gimp, as well as the starting point for getting X-input support into the gimp. 1.1.0 is the latest version AFAIK. It's slightly faster and more respoinsive than gimp's ink tool, but not nearly as useful, missing color support and all of the other bells and whistles that come with gimp. Furthermore, it only saves in PBM formats, which makes it difficult to find an alternate viewer for saved drawings. Luckily, the default version of GQView can read them.
I'd somewhat planned on trying to merge gsumi with imagemagick, netpbm and gimp, to try to retain the speed of gsumi, while adding the functionality of the other more popular applications, but for now, that's way over my head.