Step 1: Navigate to
Step 2: Copy the aero.theme file to your Desktop.
Step 3: Open up the file you just copied to your Desktop in Notepad. You can do this by
right-clicking on aero.theme > Open with > Choose default program… > Notepad
Step 4: Inside the .theme file, you will find – in the 5th line – a property called DisplayName. Change the text after
= to "Aero Lite".
Similarly, you will find a Path property near the end of the file under VisualStyles. Change the Aero.msstyles at the end of it to Aerolite.msstyles so that it can point to the files already available within Windows 8.
Step 5: Save the file and put it back under
C:\Windows\Resources\Themes, replacing the original aero.theme file. You will need administrator-level access to perform this step.
Now, from the Desktop, you can
right click > Personalize and see the file under Installed Themes. Just click on it to activate it.
Credits: RedmondPie - http://www.redmondpie.com/enable-hidden-aero-lite-theme-in-windows-8-for-slightly-improved-performance/