Why is Zend Debugger so slow to debug PHP in Eclipse?

I'm trying to debug a PHP web application hosted in IIS from Eclipse using the Zend Debugger. Unfortunately whenever I start a debug session the web server becomes very slow in serving up the pages. So slow in fact that I often get 500 errors that prevent me from debugging at all.

I've traced back the 500 errors as coming from FastCGI timing out (50 secs) but there the trace ends. How can I figure out what makes debugging so slow and fix it?

Some more details:

• Zend Debugger properly appears in php -m.
• Both the IIS web server and the Eclipse IDE are on the same machine.
• This is my personal developer machine. I'm the only one using it.
• IIS 7.5 on Windows 7 Ultimate 64-bit
• PHP 5.3.3 VC9 x86 (nts)
• Zend Engine v2.3.0 with Zend Debugger v5.3
• Eclipse Helios Service Release 2 (with PDT), Build id: 2011开发者_JAVA技巧0218-0911

First of all you can increase the fcgi timeout in the pool's configuration window.

Secondly, zend debugger works in such a way, that every included file is not loaded from disk by the PHP interpreter, but it is separately requested from the IDE. This means that every include/require your code have - leads to increased load time, because PHP does not read the file directly from disk, but sends a request to the ide debug-listener port and asks for the code. Farther explained here

There is an option in Zend Studio(link 2 an image) to switch between the modes. Can't tell you exactly where is it located in eclipse, but finding that one may actually solve your problem.