new option: COUNTERS_MAX_AGE (2)

config.php-dist

@@ -163,6 +163,11 @@
 	// to any feeds using HTTP Digest authentication and Magpie XML parsing 
 	// errors are bothering you too much, you can try enabling SimplePie.
 
+	define('COUNTERS_MAX_AGE', 365);
+	// Hard limit for unread counters calculation. Try tweaking this
+	// parameter to speed up tt-rss when having a huge number of articles
+	// in the database (better yet, enable purging!)
+
 	define('CONFIG_VERSION', 9);
 	// Expected config version. Please update this option in config.php
 	// if necessary (after migrating all new options from this file).