There is a pretty bad bug in 1.4.2b (but not in 1.4.2). If you have set the global feed update interval to 0, which normally means do not update any feeds per-default, the bug causes every feed to be updated continuously.
Please update to 1.4.3!
Workaround: If you are using 1.4.2b please ensure your default update interval is not set to zero!!!
Webmasters: Sorry!!! If you are hit by traffic from an 1.4.2b installation I'd suggest to block the user agent (e.g. "Liferea/1.4.2b (Linux; en_US; http://liferea.sf.net/)")! Using HTTP 410 you could also tell Liferea to stop updating permanently.