Using virtual nic

[cougarmaster]

First like to say sorry if this is the wrong place to ask this question as I wasnt sure where it should belong. The question is if I create a virtual nic e.g : eth0:1 and pfsense does recognise it but pfsense cant route it at all. Do I need to add routing manually or this doesnt work at all? But another problem is pfsense seems to be using more cpu than normal.