My application runs very slow in linux, red hat version 3.0. The application is installed satisfying the hardware requirements, memory, space VRAM etc.. It is installed in a network (nfs) and accessing data remotely. Application is getting hanged and crashed frequently. CPU % is shown as more than 40 when it starts to run. Can anyone reply whether this is the problem with application or network? How can I check the stability of the network? How can I improve the performance?
What else should I check to confirm whether the problem comes from the application/linux/network?

There is a program named munin that monitors various things such as cpu usage,
network usage, memory, etc. You might want to try installing that to see what
is happening on the server.

Another option is to run top which will show cpu and memory usage. It won't
show a pattern over time, but it will let you see immediately if the cpu usage
is high, if it's spending a lot of time in the wait state, or if it is swapping.

It would help to know what the application is, and does. It would also help to know if you have ever had this problem before -- is this a new application that you have never used before, or is this a new problem with an application you have used successfully before?

Used the command top and shows that this particular app takes more than 40% during start up time. Is it normal? This is a new version of the application with improved visualization. The app, in general, is slow.