User:Sharihareswara (WMF)/Performance guidelines

These performance guidelines aim to help MediaWiki developers avoid common performance problems that slow down MediaWiki and the site.

What To Do (summary)

 * Use EXPLAIN & MYSQL DESCRIBE query to find out which indexes are affected by a specific query
 * Adopt the init module pattern
 * Avoid reflows (lots of good and bad examples, ask for help)

Meta-TODO: Performance is often related to other code smells; think about root cause

Wikimedia-specific gotchas

 * image loading?
 * cache & cachebusting?