Overclocked kernels will increase the clockspeed on the tablet above what it is set to by default. For the Galaxy Tab 2 7.0 that is two cores at 1 GHz each. The overclocked kernel can boost them up to over 1.3 GHz. This is still in development and might cause crashes, so make sure do make a backup in ClockworkMod before attempting to flash this kernel.
Step 1: Download the latest version of the kernel onto your Galaxy Tab 2 7.0.
Step 2: Boot into recovery. The easiest way to do this is to hold the power button down while the tablet is on and press reboot. Then select recovery.
Step 3: Select install zip from sdcard using the volume rocker to navigate and the power button to select.
Step 4: Select choose zip from sdcard and choose the kernel you downloaded before.
You can use a program like SetCPU to adjust the clockspeed after the kernel is done flashing. If anything goes wrong then just restore from your backup in ClockworkMod.
Source: Rootz Wiki