If your laptop has intel's CPU,I strongly recommend you to install the Powertop utililty , which builds on work done by kernel developers to make the Linux kernel power-efficient.
PowerTOP needs the tickless idle (CONFIG_NO_HZ) parameter enabled in the kernel for best performance. This parameter is only in kernels 2.6.21 and above. It also needs the CONFIG_TIMER_STATS option enabled in the kernel in order to give you detailed statistics. Since most distributions have a custom kernel and maintain a development branch, grabbing a kernel using the appropriate repositories should be enough. I successfully run PowerTOP on Fedora Core 7 Test 4, which reports the kernel to be 2.6.20.
If you are using Ubuntu,to install the PowerTOP is very easy,just carry out below command on your terminal :
sudo apt-get install powertop
If you are using other linux OS or you can not install the PowerTOP from their source,you can download the latest PowerTOP tarball to install it from source.