Watch that setting! While ColdFusion MX 7 Server Configuration installs with a default value for Simultaneous Request at 8, the Multi-server configuration has a default setting of 25 for this parameter.
ColdFusion MX 7 has the same rule of thumb for starting values on this parameter, just 3 to 5 per CPU on the machine. The default Server Configuration setting falls into that range for a 2 CPU machine, but the Multiserver Configuration value of 25 Simultaneous Requests may be too high for your application.
This is one of the most important settings in ColdFusion MX server, and the best way to determine the optimal value is through good load testing during development or staging. By keeping all things the same and modulating just this setting up or down, you can plot a graph on throughput.
Most likely you would see a curve where too low a value unnecessilary limits what the server can handle, and too high a value causes excessive work to just manage so many web threads that not enough time is spent on just executing the threads. When plotting throughput on the Y axis and Simultaneous Requests on the X axis, the sweet spot would be somewhere in the middle of the throughput curve at its highest point.
Just keep any eye open for this setting when creating any new CFMX JRun server instances.
For more information on this topic, see my more recent blog entry:
activeHandlers or Simultaneous Requests: Less is More