I suggest that you look at http://bugzilla.redhat.com/ (while logged in) and do a search for CentOS.
The CentOS Project identifies (and SOLVES) many problems there. I will point you to two bugs on our bugzilla where we called out and worked in conjuection w/ Red Hat to solve problems ... there are dozens more:
0002189: CentOS is not getting optimal performance in a virtualized environment and on slow cpus - CentOS Bug Tracker
0001776: kernel panic because of a bug in the cifs module - CentOS Bug Tracker
Is Red Hat legally pirating pidgin or KDE or OpenOffice.org? Please.