[exim] MailScanner/Exim Long Queue Delay

Hi there,
This maybe a bit off topic but our of desperation, I am sending it anyway.
I have been searching in the MailScanner and Exim archives for a
solution to my problem. I have found some suggestions but none of them
worked. So here it is.
I have 3 incoming mail gateways hosting about 60K users in multiple
domains. Each process a max of 200K messages a day. For the last
months, these pesky spams have been pestering our servers causing long
delays in the delivery of emails. I have no choice but to free up the
queue using exim -q.
Anyway I read that with splitting the spool directory will somewhat
improve the server's performance. Well I tried that yesterday and was
successful only with setting that up. The problem is that emails only
get stored in the queue but not being sent out. There is no unusual
message in my logs. I know there is something wrong because emails get
delivered when I do exim -q. Has anyone actually got this
split_spool_dir to work with MailScanner already? I got my
instructions from the MailScanner website so I assumed it was going to
work but I was wrong. And sadly no troubleshooting tips nor faqs about
this.
I'm running a dual P4 3.2GHz / 2GB RAM server with MailScanner
4.58.9/exim4.66/MySQL/SpamAssassin/F-Prot/ClamAv.
And lastly since exim doesn't perform at it's best witl high queues,
what are the best workarounds for this (except for shifting MTAs of
course).

Any help/suggestion will be greatly appreciated.
Thank you!

--

Cheers,
Edward C. Jakosalem
jakosalem@???