Add a simple cache system to twitterbridge : https://github.com/mitsukarenai/twitterbridge/blob/master/index.php

index.php

<?php
// original: https://github.com/stormuk/storm-twitter + stevelacey patch
if(!isset($_GET['u'])) { header("HTTP/1.0 404 Not Found"); die('no username provided');}
$screenName = $_GET['u'];

require('StormTwitter.class.php');
require('config.php');

// configuration control
if($config['key'] == '' or $config['secret'] == '' or $config['token'] == '' or $config['token_secret'] == '') { header("HTTP/1.0 404 Not Found"); die('missing API credentials in config.php'); }

// whitelist control
$whitelist = json_decode(file_get_contents('whitelist.json'), TRUE);
if (!in_array($screenName, $whitelist)) { header("HTTP/1.0 403 Forbidden"); die('username is not whitelisted'); }

// Cache system
$cachefile = 'cache/'. sha1($screenName) .'.xml';
if( !isset($_GET['force']) && file_exists($cachefile) && filemtime($cachefile) < (time() - 900) ) {
  header('Content-type: application/rss+xml; charset=utf-8');
	echo file_get_contents($cachefile);
	die;
}

/*  START PROCESSING */
$twitter = new StormTwitter($config);

// getTweets is the only public method. For legacy reasons, it takes between 0 and 3 parameters.
// getTweets(twitter_screenname, number_of_tweets, custom_parameters_to_go_twitter); 

$twitter_data = $twitter->getTweets($screenName, 20, array('include_rts'=>true,'exclude_replies'=>true));



if($_GET['format'] == 'json')
	{
	/* JSON OUTPUT */
	header('Content-Type: application/json');
	echo json_encode($twitter_data);
	die;
	}

else
	{
	/*  RSS OUTPUT */
	// $rss is the HTML output string
	$rss = '<?xml version="1.0" encoding="UTF-8"?><rss version="2.0" xmlns:content="http://purl.org/rss/1.0/modules/content/">';
	$rss .= '<channel><title>Twitter / '.$screenName.'</title><link>http://twitter.com/'.$screenName.'</link><description>Twitter updates from '.$screenName.'.</description>';
 
	for ($i = 0; $i < 21; $i++) {
		// Tweet Text
		$desc = $twitter_data[$i]['text'];
		// Build link back
		$link = $twitter_data[$i]['id_str'];
		// Date tweet posted
		$date = $twitter_data[$i]['created_at'];
		$date = strtotime($date);

		// Build final output
		if(!empty($link))
			{ 
			$rss .=	'
			<item>
			<title>'.$desc.'</title>
			<description>'.$desc.'</description>
			<pubDate>'.date(DATE_RSS, $date).'</pubDate>
			<guid>http://twitter.com/'.$screenName.'/statuses/'.$link.'</guid>
			<link>http://twitter.com/'.$screenName.'/statuses/'.$link.'</link>
			</item>';
			}
 
		}

	// Final touch
	$rss .= '
	</channel>
	</rss>';

	// Write cache
	if( file_exists($cachefile) )
		unlink($cachefile);
	file_put_contents($cachefile, $rss);

	// Send the stuff
	header('Content-Type: application/rss+xml; charset=utf-8');
	echo $rss;
	die;
	} /* END RSS OUTPUT */

?>