[SPAM] slow local queue

Dear All,
I have installed qmail installation according to qmailrocks with mysql as data backend.
also installed local Bind as catching DNS server.

problem is that i receive lots of e-mail on daily basis and few mails are kept in my local queue for more than 4-8 hours.
what will be the issue, due to this problem my remote outqueue mails are also increasing, please suggest me some solution.
so that local mails can be cleared easily and faster.

Regards
Anil

!DSPAM:4ddc967632711902519986!