I though I'd share this on my blog in case it helps someone...

Today, I installed PHP5.5 besides a PHP 5.4 installation on one of my development VMs. This VM host several development and testing sites.

All was well until I loaded the xdebug extension... Then suddenly I saw page loads of 7 to 15 seconds on a Joomla 2.5 site which I was testing.

By disabling xdebug, everything went back to normal...

So I went and disabled some extensions like ioncube, gd, imagick but nothing helped.

I then took a look at the output of phpinfo() where I noticed that by accident I hadn't installed the mbstring extension.
Turns out, the page load times were going up because of mbstring not being installed.

After this was installed, everything was running smoothly again.
Why it only had that unexpected behavior when xdebug was turned on? I don't know.

• OS: Centos 6.5 (64)
• PHP =>v5.5.6
• Joomla => v2.5.19
• libfml => 1.3.2
• xdebug v2.2.4