Deck I gave on Optimizing WordPress at WordCamp Philly. These are a combination of my own personal experience and things we automatically do for client accounts at WP Engine.
Given the wide range in technical ability of the audience, these slides should provide an overview of subjects for optimization but you'll need to investigate the subjects individually.
6. WordPress
Optimization
Deactivate unused
plugins
+ delete plugins you don‟t use at all
WP
7. WordPress
Optimization
Avoid bad plugins
Include (but not limited to)
• backupwordpress
• backwpup
• broken-link-checker
• dynamic-related-posts
• file-commander
• google-sitemap-generator
• LinkMan (MyReviewPlugin Link Man)
• MyRP (MyReviewPlugin)
• wp-symposium-alerts
WP
8. WordPress
Optimization
Review your theme
HTML
• does it validate?
• CSS at the top, JS at the bottom (not inline)
PHP
• Any weird code (if it looks bad, it probably is)
• file_get_contents() / fgets()
WP