I am using Ubuntu Netbook remix which has ATOM processor, The Xorg CPU utilization is very high when i work on browser. I know this is because browser runs on X window. Now my question is How to reduce the CPU utiliazation of Xorg and browser. The CPU utilization is taken while running the browser is
In Atom processor : Xorg : 65-75 %
browser : 30-45%
But in Core2duo processor : Xorg : 8-15%
browser : 5-10%
Now how to reduce Atom processor utilization should be reduced as core2duo processor. Please help me. Is it possible?

That level of cpu utilization on an atom processor is probably normal. A core2duo is much more powerful than an atom processor. It's not realistic to expect similar levels of performance on a core2 duo and atom cpu.

All modern browsers tend to need a lot of cpu power and ram these days. Rendering flash video is notoriously hard on cpu usage. You may want to take a look at what firefox extensions you are using. Certain firefox extensions are known to be very hard on cpu/ram. Try disabling your firefox extensions in Tools>Addons>Extensions and see if that makes a difference. If it does, enable your extensions one at a time and see if you can isolate if one is causing a problem.

If you are running any visual effects like compiz/fusion, try turning them off. Those type of graphical effects can be very cpu intensive on a more modest cpu like an atom.

you are doing the comperation wrong.

does your Atom CPU have same speed as Core 2 Duo CPU?

even if it's actually wrong way to compare speeds, check their Hz to see if they are same or close speed.

Yes i know that atom processor will be slow. It will not work as core2duo. But my question is how to reduce the CPU utilization on ATOM.
when i type "top" in terminal i see that "compiz.real" is running..shall i remove that? if yes how to remove that?

copiz...

If you removed your compiz, you would probably reduce the load on your CPU. How much depends on what you have for a GPU and how much of the graphics work it is doing. You can try both with and then without. You can always install the compiz package again.

Running a lightweight gui, like xfce would help a lot.

I don't think you have to completely remove it. I don't have a netbook, but in standard ubuntu, if you go to System>Preferences>Appearance and then go to the Visual Effects tab and tick the "None" box, that should disable compiz temporarily.

Actually i am not using firefox. I am using QtX11 browser. I am using this for my project. I disabled compiz and still it is slow. So please tell any other way to make my browser fast.

I think the problem is with plugins. If i remove all the plugins it is some what fast. But without plugin how can i work. any suggestion will be appreciated.

I installed XFCE. But i am not getting any menu to select which desktop we want to use. it is directly going to XFCE. If i want to change to my old gdm desktop what should i do?