Broken RSS-feed blocks loding of Moodle course

A course with a RSS-block containing a non-functionning (or no-longer-existing) RSS-feed takes a very long time (>5 min) to load.
If the feed is removed, the course loads again quickly.

Example of error message in the RSS-block, when the course has finaly loaded:

http://www.swissinfo.ch/eng/rss/science_technology/index.xml Failed with code: A feed could not be found at http://www.swissinfo.ch/eng/rss/science_technology/index.xml. A feed with an invalid mime type may fall victim to this error, or SimplePie was unable to auto-discover it.. Use force_feed() if you are certain this URL is a real feed.

http://newsrss.bbc.co.uk/rss/newsonline_uk_edition/technology/rss.xml Failed with code: cURL Error: Operation timed out after 2000 milliseconds with 504 bytes received