My computer is very slow when starting applications. You clearly hear how the hard disk seems to read files from all over the disk. A first idea would be to check for fragmentation (since the drive is 80% full):
sudo e2fsck -fn /dev/sda4
returns as result that it is only 0.6% fragmented. Some further research on the web (http://blogs.kde.org/node/2270) gives me the impression that Linux file systems do not much fragment in the sense of splitting files into pieces, but they spread files in a random order over the disk (to avoid fragmentation).
Is that true?
Is there a way to force the system to place all boot files (or all files of one application etc.) in a linear order?