Could Atahualpa Theme be causing high MEM usage?

Hello. I would appreciate some help/advice.

My host Lunarpages recently informed me that I was using too many resources - CPU and MEM. I had three sites hosted on my shared account all using the Atahualpa theme. I removed one site to wordpress.com and after reading a mass of stuff about website optimisation and running my main Lunarpages site through CloudFlare the CPU usage is way down to less than 1%. But the MEM is still over 2% (it's apparently supposed to be less than this).

All comments are currently turned off for posts over 14 days old (I don't want them to be!), plugins and wordpress are up to date.

Plugins installed on leahwhitehorse.com:-

AddToAny Share/Bookmark/Email Buttons
Akismet
Easy Facebook Like Button
Feedburner Feedsmith
Googlesitemaps (I've taken off the automated redrawing of maps - I'll do it manually)
My Page Order
Wordpress Database Backup
WP-DBManager
WP Super-Cache

Plugins installed on Luatarot.com:-
Akismet
My Page Order
Page Links to
Wordpress Facebook Like Plugin
WP Supercache


Lua Tarot is on the backburner so only received about 5 views a day. Leahwhitehorse receives around 150 unique views a day (about 6000 page views since December 1st). I'm only a little fish in a big pond so really my web host's suggestion of VPS/Dedicated hosting is a bit ridiculous.

Could someone tell me whether this theme could be contributing to high MEM usage? I don't really understand what the MEM is - assuming it's memory?

I notice that a theme update is available but now I'm so worried I don't know whether if I update it, things will get even worse. I'm not having any joy getting answers from my web host and feel like I have now hit a brick wall.

Some advice would be much appreciated.

My main site is www.leahwhitehorse.com - backburner project is www.luatarot.com