Thread:Project:Support desk/Why is the ATOM feed more up to date then the RSS feed?

Sorry, no URL here since the installation is not publicly accessible.
 * MediaWiki: 1.22.5
 * PHP: 5.3.10
 * MySQL: 5.5

I've noticed that on my installation the ATOM feed of the recent changes page [1] is always more up to date then the RSS2 version [2]. I've checked the source feed and found out that both feeds have different generation times: So to me this looks like some sort of caching problem. I've tried calling action=purge on Special:Recentchanges, but that didn't help. Do you have any ideas how to get the RSS feed as up to date as the ATOM feed?
 * ATOM:  2014-04-22T14:08:50Z 
 * RSS2: Tue, 22 Apr 2014 08:20:25 GMT

P.S.: I've recently updated my installation from MediaWiki 1.16.5. I didn't noticed this issue in this old version, by the way...

[1]: index.php?title=Special:Recentchanges&feed=atom

[2]: index.php?title=Special:Recentchanges&feed=rss