Out of Memory problems in Piwik with PHP

We have done a large implementation of Piwik 1.12 with following configuration
4 web servers (Apache 2.2)
PHP 5.3.25
MySQL 5.5.31
on Windows 2008.
Daily actions are more than 1.3 Million.

The only issue is that Apache is crashing quite often. If we implement caching solutions like (APC or XCACHE), the problem increases.
The memory_limit defined is 2G and we have 4G memory on web server. I observed that apache process is not going even to 1 GB and crashes. The crashes are occuring randomly on different lines.

I believe that PHP process is not using complete 2GB of memory. The php methods memory_get_usage() doesn’t returns more than 32MB and phpinfo shows memory limit of 2G.

I have also gone through some blogs on web which says RLimitMem is the solution to this problem of apache on windows but I need solution on Windows.

Other configurations :
Schedule Report Archiving (every hour) which also started to fail.

Any help?