yum-presto not on by default

[Bill Nottingham]

Toshio Kuratomi (a.badger at gmail.com) said: 
> On 09/23/2009 10:05 PM, Bill Nottingham wrote:
> > Jonathan Dieter (jdieter at gmail.com) said: 
> >> The second one has to do with the fact that when rebuilding the rpms, we
> >> have to recompress the data, and xz compression is over 10x slower than
> >> gzip.
> > 
> > Stats of the day...
> > 
> > I took an existing xz-compressed RPM, and built a newer release of that
> > package with varying xz levels. The numbers are:
> > 
> > - the new package size at that XZ compression level
> > - the time to create a new deltarpm from a delta to that new version
> > 
> One further question -- where does libz compression fit into these stats?

zlib compressed rpm was 1756k; applydeltarpm time ~1.3 seconds. (Yes, that
implies xz -2 is faster.)

Bill