I have since gone off web-optimizer (see above) - it got too clever and too hard to keep it reliable & it kept trying to bookmark my pages in Firefox. Too hard. I am presently using http://wordpress.org/extend/plugins/wp-minify/ and Super-cache. I set the cache expiry for both to a couple of days. Once I stop tinkering (breaking things) I may set the times even longer. It's not a busy site. I find Super-cache makes for faster page loads as long as it isn't building the cache for the first viewing.
Something that has made a huge, I said H U G E, difference in page-loading times is setting long client-side expiry on everything I can and pre-Gzipping as much content as possible. These are set in .htaccess so you will need access to that. Be CAREFUL - even the slightest typo in .htaccess will take your whole site off the air - instantly! Always keep a backup / original working (!) .htaccess ready to roll-back to in a moment's notice... if you're crazy enough to experiment with it on a live site. Who me?
A good link to .htaccess info: http://www.samaxes.com/2009/01/more-on-compressing-and-caching-your-site-with-htaccess/
You will notice in the Hybrid etc. themes there are *.gz copies of CSS files etc. If you can serve these then that will cut a lot of overhead. Here's how to do that (in .htaccess) (lines starting with # are comments)
RewriteEngine on
#Check to see if browser can accept gzip files. If so and we have it - serve it!
ReWriteCond %{HTTP:accept-encoding} gzip
RewriteCond %{HTTP_USER_AGENT} !Safari
#make sure there's no trailing .gz on the url
ReWriteCond %{REQUEST_FILENAME} !^.+\.gz$
#check to see if a .gz version of the file exists.
RewriteCond %{REQUEST_FILENAME}.gz -f
#All conditions met so add .gz to URL filename (invisibly)
RewriteRule ^(.+) $1.gz [QSA,L]
I put this rule after the Super-cache rules but before the rules that get the server to gzip something that isn't already g-zipped. They get gzipped per-request so that can get expensive.
Here are some more resources for .htaccess. Remember - tread very carefully.
http://perishablepress.com/press/2006/01/10/stupid-htaccess-tricks/
http://zemalf.com/1076/blog-htaccess-rules/
... and more than you'll ever want / need to know about .htaccess, right from the source ...
http://www.askapache.com/htaccess/htaccess.html
To get an idea of what I'm talking about, check my site (http://www.CADbloke.com/) in Yslow (Firefox's Firebug plugin). Under the "components" tab note that most (hopefully all) of it is gzipped and expires in at least a few days time. Also have a look under the "statistics" tab & note how many requests are needed for a primed cache. If you have a look at the Net tab you can see what is actually being loaded. Try it by loading the page normally once of twice, then Ctrl-F5 to clear the cache and reload it. See how much was cached? That's what speeds page loads up and takes a huge load off your server.
Mostly unrelated: Irfanview is a free image viewer that has a save-for-web plugin which is very effective and eminently tweakable.
oh, btw - my site is a heavily butchered version of Hybrid News. Any feedback is more than welcome.
Hope this helps.
:)
Ewen
