Slowdown and WP HTTP Error: name lookup timed out

WP 3.3.1 with domain mapping (former WPMU)

hej,

i know this have been discussed several times, but i cant it work.

i used wp 3.2.1 and had the warnings “WP HTTP Error: name lookup timed out” in the dashboard.

i upgraded then to WP 3.3.1, but the timout warnings still appear and WP slowed down a lot! on every click i have to wait now 20 seconds.
it said after the upgrade that there was a timeout error when trying to upgrade all other network sites.

with the plugin “core control” i could log http requests and with the help of a few posts i have found out that there are really serious timeout issues and it might have something to do with cURL:

GET wp-admin/upgrade.php?step=1 error	21s	2012-03-13 14:53:24
POST /wp-cron.php?doing_wp_cron=1331646756 draft 1s 2012-03-13 14:52:37
...

even though “core control” says that the “use_curl_transport” variable is activated (true).

i followed the steps in http://wordpress.org/support/topic/dashboard-issues-rss-error-wp-http-error-name-lookup-timed-out?replies=18#post-1241599, but nothing really changed.

another issue is that if something clicks on a contact form, that it takes exactly the same time until the form is send. i guess this is the same timeout issue.

do you have an idea? i guss the issue had been in wp 3.2.1 as well.

UPDATE:

with the fantastic post of aaron at http://www.aaronfrerichs.com/tag/timeout/i found an issue in wp-admin/admin.php. “That means, each and every time an admin page loads, it tries to run the database upgrade.” when uncommenting the code there, the check for new upgrades stopped and the wordpress speed is as it was before. but the timeout issue is still the same and it seems definetly to have something to do with that.

ideas?