Railsconf had several performance-related talks. This one went over a lot of interesting territory.

• Who knew the Date class performed so badly?? Use equivalent ops in Time or get date::performance
• Use String::<< instead of String::+=
• Tune your custom sql with virtual attributes

It’s surprising that things we might not think are performance issues are problematic in ruby. One reason to optimize after you gather metrics that identify problem areas.

(Image courtesy of rowingbike.com)