Comment 8 for bug 913192

I'm against such a move.
yum metadata are bigger and slower to parse.

For updating packages, compare:
1.7M synthesis.hdlist.cz
4,4M primary.xml.gz

For retrieving metadata from rpmdrake, compare:
8,7M files.xml.lzma
11M filelists.xml.gz

And yum really is quite much slower than urpmi and I suspect the used metada format doesn't help...

As for the comment about recompressing with XZ, that wouldn't change the ration since synthesis would gain from changing compressor (we already support gz, bzip2, xz, ...)

Last but not least, it would have big impacts on perl-URPM, urpmi, rpmdrake and drakx installer.