MarkGardnerLVP - On your VPS, I would turn off Jabber if you're not using it. It's a small bonus to speed/memory. I skimmed some of your domains, and they seem to be on PHP 5.2 - I would upgrade those to 5.3 (just go to domains, edit the domain, and change PHP to 5.3 or 5.4, both use less memory than 5.2).
I'm personally a fan of Google Pagespeed, and it works well with most caching plugins (just don't use a minification plugin and pagespeed at the same time).
MrLopez, PageSpeed scores aren't the be-all and end-all of how fast your site really is. They're great for helping you understand what you might need to do to optimize things, but they don't have all the information. Like if you don't tell ySlow you're a small blog, it always yells at you about not using a CDN. Most people don't need one!
Looking at the sites in your account, one both use some Browser Caching and Gzip. It's very possible your old host was doing this for you, or a plugin you were using on the other host needs to be reconfigured for this one. The other site has an 88/100 site-speed, and the only thing I would suggest is adding in expires headers.