I recently upgraded my WP2.0.7 installation (hosted by Godaddy with no issues until this) to 2.1, and soon after I found my blog extremely unresponsive and slow. For instance it would report taking up to 12 seconds to load something simple like the Manage > Posts listing.
I later tried accessing my site only to find it was giving errors about wp-includes/cron.php. It turned out that Godaddy had removed all read access to the file. They never told me anything, but I'm assuming it was using too many resources.
Are there any known issues with cron.php in 2.1? I'm not using any plugins other than Akismet and the Backup one. Non-WP pages on the same server feel as quick to load as usual.
Edit: This is WP's bundled cron I'm talking about, NOT the wp-cron plugin, which I don't have installed.