Extremely slow speed on my site using codeignitor... is this normal?

[eluser]bretticus[/eluser]
Congratulations on optimizing your website.

Make sure you DO NOT have persistent connections enabled. It may be a performance boost in the short term but can rapidly overwhelm your database server.

To see if it is enabled, check your database.php config file. Set it to FALSE.

Code:

$config['pconnect'] = FALSE;

There may be a way to keep it on if your database server has been tuned correctly. I'm not the person to give you advice on how to do that. I generally stay away from persistent connections with MySQL because they've given me grief in the past.

I had never used Phil's caching before, so perhaps it does require a code change for every database call. It's not considered great practice, but you could alter your driver files to implement some kind of caching (I recommend using memcached since it seems like you have plenty of RAM on your server.)

You can also cache all the content depending on how dynamic your content needs to be. For example, I've seen some nifty caching where PHP is not even called. Just a static cached file via mod rewrite rules. However, to continue to let the webserver parse PHP, you should get a boost just by enabling op caching like APC right off the bat. IF you're not doing op caching, I strongly advise you to do so.

Here is a great talk by PHP creator, Rasmus Lerdorf, on PHP Performance.

Good luck.