>>>>> "David" == David Kastrup <dak@gnu.org> writes:

David> Will you fix it in Emacs or in X?

In X.

David> If the latter: is there a workaround one could use in Emacs for
David> people having an unfixed X?

In theory.  Were one to take rgb.txt (Emacs' copy will work) and convert
it into the format used by Xcms.txt (/usr/lib/X11/Xcms.txt on Gentoo,
probably the same on most other dists) then libX11 would find the colour
name when it searches that and wouldn't bother to ask the server.

Everthing before the line:

XCMS_COLORDB_START 0.1

is ignored.  As is everything after the line:

XCMS_COLORDB_END

And rgb.txt line such as:

255 250 250		snow

could look like this in Xcms.txt:

cms snow		rgb:255/250/250

Something like this perl script, which reads from either stdin or
its filename arguments and writes to stdout, should do it: