Show memory usage in Magento

To turn on memory usage and script execution time:

1. go to Admin->System->Configuration->Developer, find the ‘Profiler’ option in the ‘Debug’ section and enable it (set to ‘Yes’).

2. edit index.php and uncomment out the following line:

Varien_Profiler::enable();

The proper way to disable a module:

Go to app/etc/modules. Here you can find the list of *.xml files.

Each of them is corresponding to some extension. If you open some of the files with a text editor, you will see the following line there:

<active>true</active>

To disable the extension just change the parameter inside the ‘active’ node to FALSE in the following manner:

<active>false</active>

Remember, that’s the correct universal way to disable an extension. Do not use Admin->System->Configuration->Advanced admin page to turn off the extensions. It’s a common mistake since this tool does not disable an extension – it only disables the extension’s output. It might cause a lot of problems on your store.

Reference:

http://www.atwix.com/magento/finding-bottlenecks/