Performance

Hi,

at moment I have this environment:

CentOS nginx + phpfpm Dovecot, with Maildir format Postfix Roundcube MySQL backend about 10000 mailusers dual core Intel(R) Pentium(R) D CPU 3.00GHz 8 GB RAM network storage device (Coraid), ext4 file system

I have no performance issue now, but I need to move to a different server:

FreeBSD 10.1-RELEASE nginx + phpfpm Dovecot Postfix Roundcube dual core Intel(R) Xeon(R) CPU 5120 @ 1.86GHz 16 GB RAM local storage with zfs file system

My question is: is better to use SQLite instead of MySQL? Should I prefer dbox format?

Thank you in advance for your opinion!