Installation of the plugin is quick and simple, as usual:

script/plugin install http://svn.lightyearsoftware.com/svn/plugins/sql_logging

You're then ready to harness the power! Whilst in development mode, the plugin will add additional details to your logfile and allow you to see what's going on with your queries and where any holdups are occuring.

Rather than re-invent the wheel, i'll suggest reading the original blog post by the author of the plugin for more details.

I also periodically scan through my logs for long queries using a simple cat and grep combo to give me the 20 slowest queries:

cat log/production.log | grep "Completed in" | cut -f3 -d' ' | sort -n -r | head -n 20

Based on this I can then look through my log and identify the slow query and make efforts to improve it.