The bigger question, gone unanswered, is why your WordPress blog is configured such that three users can tap out 512MB of RAM. I run a few nontrivial WP installs averaging a couple thousand hits a day on 256MB VMs.
My hunch is that anything that actually needs to tap out 512MB of RAM should be running on a plan that's more than $10/month.
My hunch is that anything that actually needs to tap out 512MB of RAM should be running on a plan that's more than $10/month.