If Apache only used 2% of available memory, I would not be concerned. When things are quiet we have around 20 simultaneous connections.
If each instance of Apache created to service that connection uses 2-3% of memory, it is using 40-60% of system memory. If usage is under 1% per instance, we are under 20% of system memory.
Once or twice a week, the server load reaches the point where the system freezes.
Today, my biggest surprise was that Apache mysteriously dropped from using around 2.8% of memory per instance to using around 0.8%. The machine has no more RAM and I made no configuration changes.
In a near miss earlier this week, TOP reported we had just 5 megs of memory left -- one http connection away from a system freeze.
This weekend I will double the RAM in the machine. I may also upgrade to Apache2 in the hopes it will be a more efficient user of system resources.
You thought about a lame DoS attack is worth pursing.