I feel that 11.10 boots very slow on my netbook. Many people said that changing concurrency method to shell in
/etc/init.d/rc will speed up boot process, but the comment in the file said that the valid options of concurrency are 'none' and 'makefile', and the concurrency method since 2010-05-14 was makefile.
What are the differences between both? Is shell concurrency method still used until now?