diff --git a/actions/tag.php b/actions/tag.php
index 3f379ffdf2..1042513d5a 100644
--- a/actions/tag.php
+++ b/actions/tag.php
@@ -21,7 +21,6 @@ if (!defined('LACONICA')) { exit(1); }
 
 require_once(INSTALLDIR.'/actions/showstream.php');
 define('TAGS_PER_PAGE', 100);
-define('AGE_FACTOR', 864000.0);
 
 class TagAction extends StreamAction {
 
@@ -90,7 +89,7 @@ class TagAction extends StreamAction {
 		# This should probably be cached rather than recalculated
 		$tags = DB_DataObject::factory('Notice_tag');
 		$tags->selectAdd('max(notice_id) as last_notice_id');
-		$tags->selectAdd(sprintf('sum(exp(-(now() - created)/%f)) as weight', AGE_FACTOR));
+		$tags->selectAdd(sprintf('sum(exp(-(now() - created)/%f)) as weight', common_config('tag', 'dropoff')));
 		$tags->groupBy('tag');
 		$tags->orderBy('weight DESC');
 
diff --git a/config.php.sample b/config.php.sample
index 5327198bf0..8ee1f4fb46 100644
--- a/config.php.sample
+++ b/config.php.sample
@@ -71,4 +71,8 @@ $config['db']['database'] = 'mysql://laconica:microblog@localhost/laconica';
 #Do notice broadcasts offline
 #If you set this, you must run the xmppdaemon.php
 #as a daemon (with, say, start-stop-daemon)
-#$config['queue']['enabled'] = true;
\ No newline at end of file
+#$config['queue']['enabled'] = true;
+
+#exponential decay factor for tags, default 10 days
+#raise this if traffic is slow, lower it if it's fast
+#$config['tag']['dropoff'] = 86400.0 * 10;
\ No newline at end of file
diff --git a/lib/common.php b/lib/common.php
index a59e6106b2..9269ace89d 100644
--- a/lib/common.php
+++ b/lib/common.php
@@ -85,6 +85,8 @@ $config =
 			  'host' => NULL, # only set if != server
 			  'debug' => false, # print extra debug info
 			  'public' => array()), # JIDs of users who want to receive the public stream
+		'tag' =>
+		array('dropoff' => 864000.0),
 		);
 
 $config['db'] = &PEAR::getStaticProperty('DB_DataObject','options');