If you are suffering from excessive slowness from your netbook or your old and slow notebook, you may want to tweak the CPU frequency governor to performance mode instead of the general mode. How do you do that? If you are using Linux Mint, you have to install a utilities called cpufrequtils
Step 1: Install CPU Frequency Utilities
# apt-get install cpufrequtils
Step 2: Query the CPU frequency governors
Step 3: Force the CPU to use performance mode
# cpufreq-set -g performance
If this does not resolve the issues, you really have to look at other possibilities that is impacting your Xorg. Sometimes it could be your video drivers not the CPU governor issues....