CPU Usage

Hi all, Borg:

Ive been using webwizforum for 4 years now (access, then MSSQL), and again i say its a magnificient piece of software, congrats Borg and the rest of the team.

My problem is that my hosting company detected the site using a lot of cpu and referred to it as too many MSSQL requests.
It works fine at 25% of cpu usage quota, but my account only lets me have 20% quota, so i ask this:

my forum is 327.000 posts, 16.500 topics, 14.500 members, and 64 forums (i read on another topic that this is a lot)

in order to maintain a regular performance using 10% cpu what can i do?
- upgrade to 8.x? (it this new version solves the problem)
- reduce the number of forums? (i just cant)
- restrict some code, while maintaining regular use?
- upgrade to a larger hosting account?

Please take a look at my forum at http://www.motonline.pt/left/clube_motonline/forum2/index.asp (portuguese) and please help me with your advise.

Thanks a lot