I'm actually just looking at how much memory the system have free when I'm hitting on the system with a stress tool and Windows actually shows the same "issue" that Apache eats loads of memory. The maximum memory peak in the Windows environment was around 720mb and where MySql used around 30-40mb.
But, if you have a suggestion on what to specific look for and what tools to use; I will be more than happy to help out with this.
No real suggestions....
What settings are you using for:
# OS/2 MPM
# StartServers: Number of server processes to maintain
# MinSpareThreads: Minimum number of idle threads per process,
# to handle request spikes
# MaxSpareThreads: Maximum number of idle threads per process
# MaxRequestsPerChild: Maximum number of connections per server process