Question: I have a web application which i am hosting. It is working fine on my machine and most machines i try on.

My client is saying the functionality of the web application is working fine. However, it takes ages for the site to load on his machine and if he presses a button the site takes ages to process things. He has also said he has tried the site on another machine and gotten the same issue.

How can i test what is the issue on the clients machine?

Answer: 
Check your `php.ini` and see if the function that you are using to run the programs have been disabled by the `disable_functions` setting e.g.

```
disable_functions=exec,shell_exec,system,proc_open ... 

```

If the function you are using is listed, remove it.

EDIT: from the comments the solution was to set 

```
safe_mode=off

```

in php.ini.
SELinux is probably enabled. Check that with `getenforce`. If it says `Enforcing`, SELinux is most likely the blocker. You may disable SELinux temporarily (until next reboot) with command `setenforce 0`, or permanently by modifying */etc/selinux/config* and setting SELinux disabled.

Alternatively you can modify SELinux settings to be more permissive with various SELinux tools available.

**EDIT:** So it seems SELinux is already disabled. What is the exact error message you get?