[gentoo-hardened] mySQL twice as slow on hardened (grsec) sources?

[Christian Parpart]

Hi all,

I just migrated a standard gentoo/linux to a hardened profile including 
hardened-sources with grsecurity enabled and PaX-disabled.

Well, it is basically used as a mySQL server, however, we do a biig sql db 
import once a week to operate on it. the import took about 12 hours.
but now, using the hardened sourced and the hardened profile built system it 
really taked about 24+ hours.

this really confuses me. can it be because of the extra validations the 
kernel-/userspace has to perform?

mysqld still ran at 100%, before the hardened migration and after.

because *if* it is really the hardened enabled stuff that lowers the 
performance that much, than we need to revert to non-hardened - and I don't 
like that idea yet :)

Any hints on this topic are really welcome,
Thanks in advance,
Christian Parpart.