Bartlett Publishing has put together several lists of books available from many various publishers which are essential reading for anyone interested in the topic. Check them out today!
You can view the articles from the blogs which preceded these at the following URLs:
There are a lot of performance analysis tools for Rails logs. However, sometimes you just need something quick and dirty. This one helped me out. 1-line perl script to show all Rails log lines which took more that 100milliseconds to produce:
perl -n -e 'print if(m/\((\d+\.\d+)ms\)/ && $1 > 100);' log/development.log
UPDATE - Here's another handy one:
tail -20000 log/production.log|grep 'Completed in'|cut -d" " -f3,11|sort -n