As far as the guest OS is concerned it is running on standalone machine, the does not know it is running in a VMWare session. If your app runs on Linux already it will run under the VMWare image. You are not really running the program under WinXP however, you are running it under LinuxRH. Since you are emulating the hardware of a complete machine, your OS and programs will run slower than if you just ran natively on the same computer. You will have less memory and disk available as well your network interfaces will not have the complete bandwidth available to them since it shares the NIC with the host OS.
I would either port it to Windows or run on another Linux machine not running in a VMWare session.