mercury pantheon linode

I've got a Mercury 1.2 site set up on Linode and just installed a new site. In some page loads I get extremely long delays. (30 seconds or more) On other page loads, they come up almost instantly. I know the Varnish 503 error is probably because it is waiting for Apache to respond. The question becomes, why is Apache so slow??

What is the best method or analysis package for tracking down these extreme slowdowns???

thanks

I am not a professional web devloper, new to Drupal a few months ago but have learned a lot.

Want to switch to Linode and found this Pantheon Mercury stack.

http://www.linode.com/stackscripts/view/?StackScriptID=353

I have never configured a server and am wondering if it is foolish to even try to transfer my site to Linode. The benefits of VPS appear obvious with more power for less money, but I wonder if it is realistic for a non professional to maintain the site.

I am making my way through vpsBible and any similar sites for newcomers would be appreciated.

Hello all,

First thank you for all the work that has been put into Aegir and Mercury/Pantheon. I've been keeping an eye on both for a while and am ready to jump in. While my needs aren't heavy ... yet. A current project has the potential to need the power and scalability of Mercury/Pantheon and I want Aegir to make life simpler for implementing new sites and creating test development environments. So with that in mind I am creating a new server at Linode and will be migrating my sites(mostly D6 with one D5) from my old standard server.

Since I am converting from a box that wasn't using Apache/Solr, had no reverse proxy(Varnish) or caching such as APC/memcached in place I don't have to have those options fully in place on day one. I can activate those as I get a handle on their unique twists due to multi-site on Mercury/Pantheon. But I do want to lay the groundwork and get as much in place up front as I can.

I have been reading everything I can find(I'll include some of the links at the end of this post), which has answered many of my questions. But has also lead to a few more detailed new ones.