My b2evolution Version:

I moved my site to vps, installed apc, RAM 512 megabytes,
but compared to last SHARED hosting, the site became very slow, sometimes spent 3 - 7 seconds to generate the page.

My other sites on my cms at the same vps running very quickly, vps has a lot of free resources, I increased the buffer mysql, but the site is working so slowly.

Early my site on the SHARED hosting ran acceptably fast.
What could be a problem, what should I do?

sorry for my bad english