You're talking about your server load, right? You might want to try to find another host instead. Ditching vBportal would probably help as well (the script's horrible and generates a LOT of queries). One host I can highly recommend is
Pixie Host. I've had more than my fair share of problems with hosts and server loads and I would have to say they are the first that's been able to handle my site. 3,600 members, 370,000 posts, average of 40-50 users online at one time and the server load rarely rises above one. Right now I have 53 users online and the serverload is 0.26.
Not to mention they're VERY cheap. 5 gb of storage, 50 gb of bandwidth, cPanel and all that good stuff for $35/month.