VPS nginx Optimization

SO.... I've got a spiffy new VPS at MediaTemple with what will become a huge WP build and grow to around 150K+ visits per month. I'm already have 'crashing' issues with apache due to what MediaTemple says is 'apache operations limit' being maxed out. I kind of believe them, but I'm sure there's more to it. Now, the punchline: since installing WPMU on this WP build and started up the SEO plugin - the site won't load at all. It just hangs and times out. Even disabling the plugin on the server side won't bring it back. I have to restart apache, reboot the server, and it'll come back - with the SEO disabled. I am REALLY VERY SURE that there is a conflict with WP Jetpack.

Sparing you some mundane details, what I am really looking to do is make this fairly decent MediaTemple VPS SSD server rock sold and ready for whatever WordPress can do. I really like how WPMU is functioning on all of my other builds - but this one may be just to much?
Thank you for your reply.