Fresh install of WordPress 2.1.1 on a local server with no traffic. Apache 2, MySQL 5, PHP 5, etc.. everything works very fast. WordPress works extremely quickly until you edit a post then save it. That save then takes 20 seconds, and EVERY single pageload to the admin system or blog itself takes 20.xx seconds.
The only cure is to wipe the database and rerun install.php and start anew. Then it's all fast again until you update any post (creating new ones doesn't cause the problem).
There appears to be no CPU usage during this delay. And other directories containing other PHP scripts continue to work rapidly whatever's going on.. so it's a WordPress related issue.
Any thoughts? This is really odd.