VPS Server – How Much RAM

Hi All –

Looking for some suggestions. I currently have 15 WordPress Sites hosted on a VPS server. Currently I’ve got 3GBs of RAM, APACHE on sever side and cpanel on the accounts. The sites are current getting very low traffic under 1,000 hits a month, but there are three I expect to grow a lot this year.

My question is what is a good number as far as RAM to shoot for so I can grow these sites without worrying about using up all my ram? Currently on average I’m using half and one evening I had four of my writers logged into one sites and my RAM usage spiked up to:

(mysqld) score 0 vm:2858996kB, rss:47216kB, swap:498952kB

I’ve been looking at the 4.25 GB plan for Knownhost. Will that be enough for a jump in traffic and allow me to have multiple writers logged in at once to my publishing site?

Bit more information on the sites, they are optimized. Plugins range from 5-7 on most sites, I do have two big sites where I’m using 25 and 19. But the site that’s using 25 loads up well. SVT Publishing