Wordpress Multisite - Performance

Hey,

so the last 30 clients that have signed up... none have continued and I realised the performance for my sub sites are literally terrible,

check out this: http://mintybones.shopezy.co.nz/

although the page loads in less then a second it "thinks" about it for like 5 seconds.

I have 150 sub sites at the moment. I never installed the multi database thing. should I do that?