I played around some more. Now I’m back down to 45 seconds by reducing the amount of files I try to read. The libraries needed by mysql, postfix, apache are no longer included, I only try to read ahead the files for gdm. Not for X though - stracing X with the radeon driver made me stare at a black screen…

New Chart.

Generating proper readahead list files is apparently a difficult job. You need to optimize this for the critical path. I believe that manual optimization is the best here, unless you have a cheap way of logging such things.