I have several websites on a shared hosting, and I wonder if moving to a VPS will help in their page loading time performance.
(I want this to be a community wiki on the advantages of moving, but it doesn't allow me for some reason)
Dollar for dollar at the low end of VPS you will probably experience worse performance due to overselling of resources, but on the upper end you will most definitely experience better times if the original website hosting is loaded or slow.
You really should perform some testing on the current sites and see their load times, and if they are high then go from there.
Your problem likely is your are cheap. There is nothing intrinsic in a VPS that magically makes pages load faster, and a higher priced host will have mor epowerfull machiens or allow clustering eveno n a shared hosting plan.
At the end of the day, a VPS is a simulated computer. That is less efficient on many layers than shared hosting. It means loading a new oepratig system (more memory, processor overhead) compared to a shared host which runs on the same OS / the web servers virtual facilitie. This means you HAVE to pay more, item per item, to get the same perforamcne. More overhead = higher costs. And, btw., you better know what you are doing. Because you then are responsible for adminsitrating it.
On the high end, a VPS will scale worse than a nice transparently managed shared hosting cluster (there are some providers out offering this).
The core functionality of a VPS is to allow customization way above and beyond what shared hosting offers, not to be a cheaper alternative. So, at the end, if you need more page load times, you can: * Become a better programmer. Espeically in the web area, a decent profiler may be your best investment. * Upgrade your host to one offering more power. Because if you run cheap on shared hosting, then the host has no alternative than to overload the hosts. The computers dont magicvally become cheaper because you are a host.
At the end, it is about money. And a VPS will notch up your expenses first, because of higher technical overhead.