I am using i-5 8 core processor and when I am using Centos 6.4 System Montitoring tools, the CPU-1 goes to 100. This will slow down the other process such as the mouse movement.

Is this a normal behaviour? Is this going to effect any process running on the other cup cores?
I used top command to minitor the CPU resource. Problem I have is that any x-window menue uses lots of resource. For example if I take the firefox and move it around the monitor, the xorg cup usage goes to 100.

What system monitor tools? What is using the CPU? Have you tried top?

Also - there are no 8 core i5 processors. Maybe you mean a quad core with hyperthreading?

...

What are you using for graphics? Do you have a dedicated card or some chip built into the mobo or CPU? Also have you tried a lighter weight DE?

This is what I got from the following command. Does it mean that i have a 8 core processor?
[root@rpcxft ~]# cat /proc/cpuinfo | grep -i 'core id'
core id : 0
core id : 1
core id : 2
core id : 3
core id : 0
core id : 1
core id : 2
core id : 3

No, that means you have a quad core processor. An 8-core processor would have core ids from 0-7, not two copies of 0-3. You could get that output from a dual processor machine running 2 quad core procs, but the i5 can't be used in a dual processor machine, so that's impossible if you really have an i5. If you check the physical id from cpuinfo you'll see they're all the same, which means it's a single proc quad core machine with hyperthreading. You could also just google the model number from cpuinfo and it would tell you the same thing - 4 cores with 8 threads.

You were right. the processor is 4 core and 8 threads. Any idea why the Xorg cpu usage is high?

3214 root 20 0 87112 46m 8236 R 88.8 0.3 2:15.39 Xorg
2995 operator 20 0 82984 3124 2264 S 7.3 0.0 1:03.72 rcp8
128 root 39 19 0 0 0 S 1.0 0.0 0:36.71 kipmi0
3820 radarop 20 0 406m 82m 29m S 0.7 0.5 0:16.35 firefox
1818 root 20 0 0 0 0 S 0.3 0.0 0:00.08 kondemand/3
3470 radarop 20 0 99.1m 10m 8688 S 0.3 0.1 0:00.74 metacity
3472 radarop 20 0 103m 19m 13m S 0.3 0.1 0:00.96 nautilus
3497 radarop 20 0 57160 11m 9596 S 0.3 0.1 0:00.65 wnck-applet
1 root 20 0 2900 1428 1200 S 0.0 0.0 0:01.18 init
2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kthreadd

Please see my earlier post on the subject:

I had a built in graphic card and I after I used an external one, the Xorg usage dropped to 30%.

Thanks

So Xorg was what was using the CPU so much? And using an external graphics card helped? It sounds like the issue was just a lack of hardware acceleration. Can you confirm or deny this?

Sorry if I sound like I'm badgering, I just want to make sure that future readers of this thread have some idea of what's going on. LQ is pretty high on Google's rankings, and I've come across several threads where the OP just said "Oh, I fixed it, bye" without posting any hints of what the solution was.

the issue was just a lack of hardware acceleration and using an external graphic card reduced the Xorg usage from %100 (everytime I drag a menu and move it around)to %30 in the same test condition.

Save penguin power: