Paginate Processor Load

Sorry for the late reply. I didn't see your post. The forum doesn't always send email notifications when there's new replies...
Anyway, maybe your performance problem has something to do with session locking. If the front-end makes multiple ajax queries at the same time, you can have performance issue where one query is waiting for the session lock to be released. Calling session_write_close() as early as you can, as soon as you no longer need the session data can help with this. Especially while you wait for the database query to return, you probably no longer need session data at this point.

Only MySQL and PostgreSQL databases are officially supported, due to lack of advisory locking mechanisms on other platforms. Using sessions without locks can cause all sorts of problems, especially with heavy usage of AJAX, and we will not support such cases. Use session_write_close() after you’ve done processing session data if you’re having performance issues.

Source: http://codeigniter.com/user_guide/librar...sions.html