Situation:
Operating System: Windows 7 Pro
PHP: version 5.6.18 x32 NTS for IIS version 7.5
Symfony: version 2.8.4

With above configuration, symfony does not start anymore at least in debug mode (not checked in prod mode); analyzing with debugger, the program appears to loop endlessly at line 292 of file "DebugClassLoader.php".

Checking the differences between this version and version 2.8.3, it seems that problem starts assigning the value 2 to variable $caseCheck at line 62; changing in this line the value "= 2" with "= 1" the problem is resolved; obviously this is a workaround in order to work, not a definitive solution.

It's easy to reproduce the problem: install a new LTE symfony project, update it to version 2.8.4 and run it in dev mode (/web/app_dev.php). It hangs.

In my opinion the problem is in the resolution of following issue:

[Debug] Replaced logic for detecting filesystem case sensitivity #18126, #18130

Maybe the correct code at line 60 of above mentioned file should be:

} elseif((false !== stripos(PHP_OS, 'win')) && (false === stripos(PHP_OS,'darwin')) || realpath(strtolower(__FILE__)) === __FILE__) {
// filesystem is not case sensitive or is Windows!