Hello,
If I enable the function set_time_limit. What wrong could happen in my server? Do you you think it could compromise the security on it?

Thanks
Mike

security compromise: yes, but not too serious.
You should know:
- set_time_limit is always disabled with safe_mode ON
- just a few seconds fork bomb is many times dangerous than a many-minute-during script.
So, IMHO, you should enable set_time_limit when possible.