I did some quick profiling with oprofile of an anaconda install and the vast majority of the total install time is spent waiting in the idle loop in the kernel. However I was doing an NFS install, which is pretty much reading the RPM over the network and exploding it to disk. The bytes/sec we were exploding RPMs in anaconda was about 50% of what you get if you just 'rpm2cpio | cpio -dimv ' the same RPMs to the drive (I tried this as a test).
Its something we want to revisit when we have time. To be honest you're only reinstalling once ever 6-12 months and then using up2date to keep the system current, so it hasn't been a high priority to reduce the install time by 30% as compared to clearing out as many bugs and adding features which will make anaconda most useful. I'll be happy the day all the complaints about anaconda are just performance related.
Michael Fulbright msf@redhat.com